Autoimmune Hemolytic Anemia

C H A P T E R

47 Autoimmune Hemolytic Anemia Mark A. Vickers1,2 and Robert N. Barker2 1

Scottish National Blood Transfusion Service, Aberdeen, United Kingdom 2Immunity, Infection and Inflammation, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom

O U T L I N E Historical Background

897

Treatment of Autoimmune Hemolytic Anemia

903

Classification of Autoimmune Hemolytic Anemia

898

Etiology of Autoimmune Hemolytic Anemia and Predisposing Factors Genetic Predisposition Gender and Age Infectious Agents Drugs Neoplasia

903 903 904 904 904 904

Animal Models of Autoimmune Hemolytic Anemia Mechanisms of Red Blood Cells Destruction in Autoimmune Hemolytic Anemia Cold Reactive Antibodies Warm Reactive Antibodies Pathogenicity of Warm Reactive IgG Antibodies Additional Mechanisms of Hemolysis by Warm Antibodies Red Blood Cell Autoantigens

898 899 899 899 899 901 902

Clinical Signs of Autoimmune Hemolytic Anemia

902

Laboratory Diagnosis of Autoimmune Hemolytic Anemia

902

Immune Mechanisms Underlying Loss of Self Tolerance in Warm Autoimmune Hemolytic Anemia 904 B Cells and Tolerance 905 T-Helper Cells and Tolerance 905 Concluding Remarks

906

References

906

HISTORICAL BACKGROUND The earliest descriptions of autoimmune hemolytic anemia (AIHA) date from the 19th century, and the disease was one of the first shown to have an autoimmune pathology. Pioneering work by Donath and Landsteiner (1904) demonstrated that the destruction of red blood cells (RBC) was dependent on the absorption of hemolysins and complement from serum. Further studies were impeded by the difficulty in distinguishing acquired from congenital hemolytic anemias, but an important advance was made using the antiglobulin, or Coombs’, test, which detected RBC coated with autoantibodies by agglutinating them with antiserum to human globulin (Coombs et al., 1945; Boorman et al., 1946; Loutit and Mollison, 1946). Methods for measuring survival of circulating cells in vivo further demonstrated that RBC from patients with acquired hemolytic anemias were destroyed by a “random hemolytic process,” rather than being “intrinsically defective” (Loutit and Mollison, 1946; Mollison, 1959). Together, these developments identified AIHA as a disease in which autoantibodies bind

The Autoimmune Diseases, 6th. DOI: https://doi.org/10.1016/B978-0-12-812102-3.00047-6

897

Copyright © 2020 Elsevier Inc. All rights reserved.

898 TABLE 47.1

47. AUTOIMMUNE HEMOLYTIC ANEMIA

Classification of Autoimmune Hemolytic Anemia (AIHA) Cold reactive

Warm reactive

CLASSIFICATION BY AUTOANTIBODY TYPE Optimum temperature for binding RBC

4 C

37 C

Predominant autoantibody class

IgM (cold agglutinin syndrome)

IgG

IgG (paroxysmal cold hematuria) Predominant site of hemolysis

Intravascular

Extravascular (spleen, liver)

Predominant mechanism of hemolysis

Complement lysis (membrane attack complex)

Phagocytosis via macrophage IgG Fc and complement receptors

CLASSIFICATION BY UNDERLYING DISEASE Primary (idiopathic)

Secondary

No underlying disease

Underlying disease (causal or shared etiology) Infection Other immune disease neoplasia Drug induced

RBC and shorten their lifespan, affecting 1 3 per 100,000 of the population (Sokol et al., 1992; Petz and Garratty, 2004a).

CLASSIFICATION OF AUTOIMMUNE HEMOLYTIC ANEMIA AIHA can be classified both by the type of autoantibody and by the presence of underlying disease (Sokol et al., 1992; Petz and Garratty, 2004a) (Table 47.1). Pathogenic autoantibodies are divided into either cold (Petz, 2008) or warm (Packman, 2008) reactive, depending on the optimum temperature at which they bind RBC. Up to 7% of the patients have “mixed” pathogenic autoantibodies of both types (Sokol et al., 1981, 1983, 1992). AIHA can also be described as primary, or idiopathic, in the absence of any associated condition, or as secondary if there is a concurrent disease that may be considered causal or has shared etiology (Packman, 2008; Petz, 2008).

ANIMAL MODELS OF AUTOIMMUNE HEMOLYTIC ANEMIA Examples of AIHA in laboratory mice have proved valuable in understanding the pathogenesis of the disease. The New Zealand Black (NZB) mouse (Helyer and Howie, 1963; Barker et al., 1993b) develops AIHA spontaneously, and hemolysis can be recapitulated by transgenic expression of a monoclonal anti-RBC autoantibody derived from this strain (Murakami et al., 1992). AIHA is also one of the autoimmune pathologies arising in the nonobese diabetic mouse (Baxter and Mandel, 1991) and from genetic modification to prevent expression of interleukin-2 (IL-2) (Hoyer et al., 2009). In addition to these spontaneous examples, the disease can be induced in healthy murine strains by repeated immunization with rat RBC (Playfair and Marshall-Clarke, 1973; Naysmith et al., 1981) or by infection of C3HeB/FeJ mice with the docile strain of lymphocytic choriomeningitis virus (LCMV) (Coutelier et al., 1994). AIHA has also been described as a cause of anemia in the domestic dog (Barker et al., 1991), cat (Switzer and Jain, 1981), rabbit (Fox et al., 1971), horse (Mair et al., 1990), and ox (Dixon et al., 1978).

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

MECHANISMS OF RED BLOOD CELLS DESTRUCTION IN AUTOIMMUNE HEMOLYTIC ANEMIA

899

MECHANISMS OF RED BLOOD CELLS DESTRUCTION IN AUTOIMMUNE HEMOLYTIC ANEMIA AIHA is a classic example of type II hypersensitivity, with autoantibody-coated RBC removed from the circulation by phagocytes of the reticuloendothelial system (RES), predominantly splenic macrophages, and/or lysis by complement fixation (Packman, 2008; Petz, 2008). Anemia results if the hemolysis is insufficiently compensated for by increased RBC production.

Cold Reactive Antibodies Cold reactive anti-RBC autoantibodies are responsible for 15% 20% of human AIHA cases (Petz, 2008). They bind more strongly at 4 C than at higher temperatures, and the pathogenic effects of these antibodies depend more on their thermal amplitude than their titer. Cold autoagglutinins that bind RBC below 10 C 15 C can be demonstrated in the sera of most healthy individuals (Landsteiner and Levine, 1926). In contrast, cold autoantibodies active up to 30 C are associated with cold agglutinin syndrome (CAS) (Petz, 2008), since temperatures in the peripheral circulation can fall below this level. The antibody, usually immunoglobulin (Ig) M, causes intravascular hemolysis if it activates complement to form membrane attack complexes (MAC) (Engelfriet et al., 1981; Petz and Garratty, 2004b), overcoming protective regulators on the RBC such as CD35 (complement receptor 1 CR1), CD55 (decay-accelerating factor), and CD59 (protectin) (Nicholson-Weller et al., 1982; Krych-Goldberg and Atkinson, 2001; Ruiz-Argu¨elles and Llorente, 2007). RBC coated with C3b may also be temporarily sequestered by macrophages (Engelfriet et al., 1981). In some patients, cold IgM autoantibodies agglutinate RBC in extremities that become chilled, blocking small blood vessels and causing ischemia (Petz, 2008). CAS can be either transient, most frequently as a complication of mycoplasma infection (Costea et al., 1972), or chronic, typically associated with clonal lym-phoproliferative disease (Berentsen et al., 2006). Pathogenic cold reactive autoantibodies also include the Donath Landsteiner (DL) hemolysins, which cause paroxysmal cold hemoglobinuria (PCH), a dramatic form of AIHA precipitated by chilling of the patient (Petz, 2008). These antibodies, which are IgG, bind RBC if the temperature falls below 37 C, and then fix complement to trigger MAC formation and fulminant intravascular hemolysis when warmed again. PCH was commonly secondary to syphilis when it was first described in the late 19th century but is now rare and typically follows childhood viral infections (Sokol et al., 1982, 1984, 1999).

Warm Reactive Antibodies Warm autoantibodies are the most common cause of AIHA and react as well, or more strongly, with RBC at 37 C than at lower temperatures (Sokol et al., 1992; Packman, 2008). Most are of the IgG class and cause extravascular hemolysis, predominantly by Fc receptor (FcγR) mediated phagocytosis (Engelfriet et al., 1981; Petz and Garratty, 2004b; Packman, 2008). The complement regulators on the RBC membrane (Ruiz-Argu¨elles and Llorente, 2007) typically prevent MAC formation, but deposition of C3b and C3d is common and can strongly enhance opsonization (Kurlander et al., 1978) by interacting with specific receptors including CR1 and CR3 (Ross and Medof, 1985). Although blood monocytes and hepatic Kupffer cells also express appropriate sets of receptors, splenic macrophages are the main effectors of RBC destruction (Engelfriet et al., 1981; Petz and Garratty, 2004b; Packman, 2008). Some sensitized RBC may be only partially phagocytosed and released back into the circulation as spherocytes, which have a short half-life (Garratty, 1983). Between 22% (Dausset and Colombani, 1959) and 81% (Pirofsky, 1976) of warm AIHA cases have been reported to be secondary, varying with different interpretations of this classification. The most common associations are with other immune-based conditions, most notably ulcerative colitis, rheumatoid arthritis, and systemic lupus erythematosus (SLE), with neoplasia, particularly chronic lymphocytic leukemia (CLL), with a growing number of drug treatments (Garratty and Arndt, 2014), and with a variety of infectious diseases (Sokol et al., 1992; Petz and Garratty, 2004a).

Pathogenicity of Warm Reactive IgG Antibodies Warm reactive IgG anti-RBC autoantibodies vary in their pathogenicity, exemplified by the finding of a positive direct agglutination test (DAT) in a small proportion (1 in 7 15,000) of healthy blood donors (Hernandez-

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

900

47. AUTOIMMUNE HEMOLYTIC ANEMIA

Jodra et al., 1990; Win et al., 1997; Petz and Garratty, 2004b). The ability to cause hemolysis has been attributed to multiple factors, including titer, subclass, affinity for autoantigen, patterns of heavy chain glycosylation, and also the activity of phagocytes responsible for clearance (Garratty, 1990; Sokol et al., 1992; Petz and Garratty, 2004b). The amount of IgG blood group alloantibody-coating RBC determines their rate of clearance in healthy subjects (Mollison and Hughes-Jones, 1967; Kelton et al., 1985), but it is less easy to demonstrate a similar relationship for autoantibodies in human AIHA (Rosse, 1971; Chaplin, 1990; Petz and Garratty, 2004b). Serial measurements from individual patients reveal some correlation of hemolysis with autoantibody titer, but many cross-sectional studies fail to do so, using either the DAT or more sensitive and quantitative flow cytometric or ELISA-based techniques to measure RBC-bound IgG (Van der Meulen et al., 1980; Garratty and Nance, 1990; Sokol et al., 1992; Petz and Garratty, 2004b). Autoantibody titer alone also appears to be an unreliable predictor of the severity of hemolysis in canine (Barker et al., 1992b) and murine AIHA (Naysmith et al., 1981; Shen et al., 2003). The subclass of RBC autoantibody is a potentially important factor in its ability to cause hemolysis, by determining interactions with different types of FcγR and fixation of complement (Sokol et al., 1992; Petz and Garratty, 2004b). Comprehensive analyses of IgG subclass switch variants of monoclonal anti-RBC antibodies originally derived from NZB mice have established how differences in these Fc-associated effector functions can critically influence pathogenicity (Baudino et al., 2006), with affinity for autoantigen playing a less important role (Fossati-Jimack et al., 1999). In mice there are three activating FcγR types (FcγRI, FcγRIII, and FcγRIV), all of which are expressed on macrophages and can bind complexed IgG, while only FcγRI also has high affinity for monomeric IgG (Nimmerjahn and Ravetch, 2008). IgG2a and IgG2b autoantibody switch variants, each of which interacts efficiently with FcγRIII and activate complement, and mediate the most severe hemolysis in vivo (Baudino et al., 2006). FcγRIV makes an additional contribution to uptake by these isotypes, and IgG2a also promotes clearance via FcγRI if it coats RBC at sufficient density to compete with the free monomer in serum (Baudino et al., 2008). The next most pathogenic subclass is IgG3, which activates complement but does not bind any FcγR, followed by the IgG1 subclass that interacts only with FcγRIII and fails to fix complement. Overall, IgG2a and IgG2b autoantibodies are 20-fold more potent in causing hemolysis than IgG1 (Baudino et al., 2006). Complement fixation by the murine autoantibodies does not lead to MAC formation, but CR-mediated erythrophagocytosis can be important if there is an extensive opsonization of RBC by C3 associated with binding of high-affinity IgG2b or IgG3 (da Silveira et al., 2002). Compared with murine studies, the relationships between human RBC autoantibody subclass and hemolysis are less clear (Petz and Garratty, 2004b). Based on interactions with FcγR and complement, IgG3 would be predicted to be the most pathogenic subclass, followed by IgG1, with IgG2 and IgG4 relatively benign (Engelfriet et al., 1981; Petz and Garratty, 2004b; Sokol et al., 1992). However, in both patients with AIHA and healthy DAT-positive donors with no evidence of hemolysis, IgG1 autoantibody predominates and is the only isotype detected on RBC using agglutination-based techniques in up to 80% of each group (Garratty, 1989). Furthermore, IgG3 can be detected by DAT not only in patients but also in normal blood donors, although RBC sensitization with IgG4 alone may be restricted to healthy individuals (Garratty, 1989). Sensitive flow cytometric and ELISA methods (Sokol et al., 1990a; Garratty and Nance, 1990) have confirmed that increased levels of RBCbound IgG3 are not necessarily associated with disease and suggest instead that autoantibodies of multiple IgG subclasses are common in AIHA and that this diversity is important in promoting hemolysis via synergistic effects (Sokol et al., 1990a). The three families of human activating FcγR (FcγRI, FcγRIIa/FcγRIIc, and FcγRIIIa/ FcγRIIIb) (Nimmerjahn and Ravetch, 2008) may each play a role in RBC uptake. As in mice, only FcγRI has a high affinity for monomeric IgG but may mediate erythrophagocytosis under conditions that allow RBC-bound IgG to compete with a monomer in serum, particularly in the hemoconcentrated environment of the spleen (Kelton et al., 1985; Barker et al., 1992b). Although MAC formation rarely contributes to hemolysis in the patients with warm antibodies, complement fixation appears to be an important determinant of disease (Petz and Garratty, 2004b). C3 can be detected by DAT in up to 50% of AIHA patients (Garratty, 1989) and is quantitatively associated with hemolysis (Freedman et al., 1982), reflecting synergy between FcγR and CR in RBC uptake (Sokol et al., 1992). Changes in glycosylation of the CH2 domain of the IgG heavy chain may also influence interactions with FcγR and complement, with loss of either terminal sialic acid or galactose residues suggested to alter the pathogenicity of murine RBC autoantibody (Baudino et al., 2006). There is evidence in rheumatoid arthritis that IgG lacking galactose (G0) can interact with mannose-binding protein, thereby fixing complement and triggering inflammation (Malhotra et al., 1995). However, in AIHA it seems likely that RBC autoantibody may be less hemolytic than G0, since the loss of galactose reduces the affinity of IgG for FcγRIII (Hadley et al., 1995). Although G0 RBC

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

MECHANISMS OF RED BLOOD CELLS DESTRUCTION IN AUTOIMMUNE HEMOLYTIC ANEMIA

901

autoantibodies have been identified in some AIHA patients and in NZB mice, the levels can vary widely over time in individuals and show no correlation with the severity of the disease (Barker et al., 1999a,b). The final, important, factor determining the hemolytic potential of warm autoantibodies is the effectiveness of the RES in clearing sensitized RBC (Sokol et al., 1992; Petz and Garratty, 2004b). The ability of macrophages to phagocytose RBC can be enhanced by infections that upregulate FcγR expression (Atkinson and Frank, 1974; Coutelier et al., 2007) or compromised by saturation with immune complexes in AIHA secondary to SLE (Frank et al., 1979). Drugs such as corticosteroids can also inhibit phagocytosis by downregulating FcγR expression (Fries et al., 1983; Kelton, 1985). The cytokine milieu is a major influence on macrophage activation state, and the severity of NZB AIHA can be ameliorated by gene therapy to increase levels of circulating IL-4 (Youssef et al., 2005).

Additional Mechanisms of Hemolysis by Warm Antibodies Although FcγR- and CR-mediated erythrophagocytosis of IgG-coated RBC is the major cause of hemolysis in warm AIHA, there is evidence for other pathogenic mechanisms (Sokol et al., 1992; Petz and Garratty, 2004b). In rare patients with warm AIHA, the main autoantibody class may be IgM or IgA, and not IgG. If warm IgM autoantibodies predominate, they can trigger MAC formation and fulminant intravascular hemolysis (Freedman et al., 1987). IgA autoantibodies may cause hemolysis by Fc-mediated uptake and cytotoxicity (Clark et al., 1984), or hemagglutination in the spleen (Baudino et al., 2007). More sensitive techniques than the DAT detect a higher prevalence of cosensitization of IgG with low levels of IgM and/or IgA, and such coating of RBC with multiple antibody classes is associated with severe hemolysis, suggesting the importance of synergistic effects (Sokol et al., 1990b). TABLE 47.2 Red Blood Cells Autoantigens in Human Autoimmune Hemolytic Anemia (AIHA) Caused by Cold Autoantibodies Form of AIHA

Common autoantibody Specificity

Rare autoantibody Specificity

CAS

I (B90% patients)

i, Pr, A, B

PCH

P (B90% patients)

i, p, HI, I

CAS, Cold agglutinin syndrome; PCH, paroxysmal cold hematuria.

TABLE 47.3 Red Blood Cells (RBC) Autoantigens in Human and Animal Autoimmune Hemolytic Anemia (AIHA) Caused by Warm Autoantibodies Species

B-cell autoantigen (dominant antigen in bold)

Th-cell autoantigen identified

Unprimed autoreactive Th cells in health

Regulatory T-cell response

Human AIHA

Rh proteins (B70% patients)

Rh proteins

Yes

IL-10 response to Rh protein

Glycophorin A

Epitopes

Band 3 Canine AIHA

Glycophorins (B50% patients)

Glycophorins

Yes

Not examined

Band 3

Not applicable

Weak IL-10 response to

Band 3 Murine AIHA NZB mouse

Band 3 Band 4.1 (pr)

Band 3

Phosphatidylcholine (pr) Induced by rat RBC

Band 3 (cr) Glycophorins (cr)

Band 3

Yes

Recovery due to suppression by CD251 cells

Induced by LCMV

Band 3

Not examined

Yes

Not examined

Pr, Polyreactive antibody also binds nuclear antigens, for example, histones; cr, cross reacts with rat RBC antigen. Modified from Barker, R.N., Vickers, M.A., Ward, F.J., 2007. Controlling autoimmunity—lessons from the study of red blood cells as model antigens. Immunol. Lett. 108, 20 26 (Barker et al., 2007).

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

902

47. AUTOIMMUNE HEMOLYTIC ANEMIA

Another mechanism, which may be of particular relevance in patients with very low levels of RBC-bound IgG, is that splenic macrophages are instead “armed” with the autoantibody bound to FcγRI, allowing them to capture circulating RBC (Griffiths et al., 1994). Antibody-dependent cell-mediated cytotoxicity may also play a role in hemolysis (Garratty, 1983; Griffiths et al., 1994), mediated not only by macrophages but also potentially by K cells (Urbaniak and Griess, 1980) or activated neutrophils (Engelfriet et al., 1981). In some patients, there is evidence that autoantibodies can interfere with erythropoiesis (Crosby and Rappaport, 1956) or RBC egress from the bone marrow (Conley et al., 1982), as well as causing hemolysis.

Red Blood Cell Autoantigens Many of the major RBC autoantigens in AIHA have been identified (Tables 47.2 and 47.3). Serological studies have established that cold reactive RBC autoantibodies in healthy individuals, and pathogenic species with high thermal amplitude in CAS, are most commonly directed to the Ii blood group system of carbohydrate differentiation antigens (Berentsen and Tjønnfjord, 2012). On adult RBC, the I antigen predominates, while i is expressed at low levels. Antibodies from approximately 90% of CAS patients recognize the I antigen (Jenkins et al., 1960), with anti-i (Marsh and Jenkins, 1960) accounting for most of the remainder. Other, very rare specificities for autoantibodies in CAS include Pr (Dellagi et al., 1981). In PCH, anti-P autoantibodies are detected in at least 90% of the patients (Sokol et al., 1999). The most common targets in human warm AIHA, recognized in over 70% of cases, are the Rh proteins (Weiner and Voss, 1963; Barker et al., 1992a; Leddy et al., 1993), which also express important blood groups (Avent and Reid, 2000). Autoantibodies reactive against the glycophorins, or against the RBC anion channel protein, Band 3, are produced in some patients (Victoria et al., 1990; Barker et al., 1992a; Leddy et al., 1993). The major canine RBC autoantigens are the glycophorins, with autoantibodies from some cases specific for Band 3 (Barker et al., 1991). In mice, Band 3 is the dominant autoantigen in NZB disease (Barker et al., 1993b; de Sa´ Oliveira et al., 1996) and in AIHA following LCMV infection (Mazza et al., 1997) and, together with glycophorins, is also a target for autoantibodies induced by rat RBC (Barker et al., 1993a). In addition to the autoantigens relevant to AIHA pathogenesis, RBC can also express cryptic determinants recognized by naturally occurring IgG autoantibodies. These include spectrin, the major component of the internal RBC cytoskeleton (Lutz and Wipf, 1982; Ballas, 1989; Barker et al., 1991, 1993a) and senescent red cell antigen (Alderman et al., 1981), which is exposed on Band 3 by aged RBC (Kay et al., 1990). The autoantibodies are thought to provide physiological mechanisms for disposing of damaged and effete RBC (Wiener et al., 1986; Pantaleo et al., 2008).

CLINICAL SIGNS OF AUTOIMMUNE HEMOLYTIC ANEMIA In both CAS (Petz, 2008) and warm AIHA (Packman, 2008), the predominant clinical features reflect the anemia, which most commonly causes lethargy and dyspnea. Signs include pallor and icterus, and massive hemolysis may precipitate hemoglobinuria. In CAS there may also be cyanosis or even necrosis of the bodily extremities (Petz, 2008). AIHA due to DL antibodies is typified by recurrent bouts of anemia and hemoglobinuria precipitated by exposure to cold (Petz, 2008). In warm AIHA, splenomegaly or hepatomegaly can be associated with extravascular hemolysis (Packman, 2008). Where AIHA is secondary, the signs of the underlying disease may predominate.

LABORATORY DIAGNOSIS OF AUTOIMMUNE HEMOLYTIC ANEMIA In addition to anemia, most cases show evidence of erythroid regeneration, with reticulocytosis (Packman, 2008; Petz, 2008). However, there can be a poor erythroid response (Liesveld et al., 1987), due to the physiological lag in increasing RBC production following acute hemolysis, or to autoimmune reactions inhibiting RBC regeneration (Conley et al., 1982), or to an underlying bone marrow disorder (Lefrere et al., 1986). Evidence of hemolysis can also be provided by increased bilirubin, aspartate transaminase, and lactate dehydrogenase levels. RBC autoagglutination or spherocytes may be seen in cold and warm AIHA, respectively.

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

ETIOLOGY OF AUTOIMMUNE HEMOLYTIC ANEMIA AND PREDISPOSING FACTORS

903

Detection of RBC autoantibodies confirms the diagnosis of AIHA. The DAT has been the classic tool for measuring RBC-bound autoantibodies and complement (Petz and Garratty, 2004a). However, benign immunoproteins on the RBC surface can cause a positive DAT (Heddle et al., 1988; Huh et al., 1988), and the test also gives false-negative results in 3% 11% of AIHA cases (Sokol et al., 1985, 1988; Petz and Garratty, 2004a). These limitations have led to more sensitive methods to detect RBC-bound immunoglobulins, including radioimmunoassay (Kaplan and Quimby, 1983), flow cytometry (Van der Meulen et al., 1980; Garratty and Nance, 1990), or ELISA (Sokol et al., 1985, 1988).

TREATMENT OF AUTOIMMUNE HEMOLYTIC ANEMIA Anemia in both cold and warm AIHA requires supportive care and, if life-threatening, transfusion (Packman, 2008; Petz, 2008). Patients with pathogenic cold reactive autoantibodies should be protected from unnecessary exposure to low temperatures (Petz, 2008). Cases of secondary disease, for example, CAS or PCH associated with infection, may be transient or resolve with treatment of the underlying condition. Corticosteroids or cytotoxic drugs have been used to treat CAS, but the response is frequently poor (Petz, 2008), and better results have been obtained by targeting B cells with the anti-CD20 monoclonal antibody rituximab (Berentsen et al., 2004), which is now considered the first line of therapy (Zanella and Barcellini, 2014). Corticosteroids, such as prednisolone, are the most common first-line therapy for warm AIHA and can be highly effective, although many patients relapse after withdrawal of these drugs (Packman, 2008). Corticosteroids can both downregulate macrophage FcγR to improve the survival of IgG-sensitized RBC (Fries et al., 1983) and reduce autoantibody production (Rosse, 1971; Sokol and Hewitt, 1985), but the rapid response they typically elicit suggests the importance of the former effect (Packman, 2008). Cytotoxic drugs such as cyclophosphamide or azathioprine may be used as second-line therapies to suppress immune responsiveness, or splenectomy can also be considered to remove a major site of extravascular hemolysis (Packman, 2008; Crowther et al., 2011). Ablation of B cells with rituximab has emerged as an effective treatment for AIHA that is refractory to conventional treatments (Zecca et al., 2003; Pen˜alver et al., 2010; Crowther et al., 2011), is now the preferred second-line therapy after corticosteroids in some centers, and also shows promise as a first-line treatment when combined with steroids (Dierickx et al., 2015).

ETIOLOGY OF AUTOIMMUNE HEMOLYTIC ANEMIA AND PREDISPOSING FACTORS It is clear that autoimmune diseases result from the interaction of multiple factors (Shoenfeld and Isenberg, 1989; Cho and Gregersen, 2011). Genetic background, gender, age, environmental factors such as infections, drugs, and neoplasia have all been implicated in the etiology of AIHA.

Genetic Predisposition The possibility of a genetic predisposition to human AIHA was raised by rare reports of familial disease (Cordova et al., 1966; Pirofsky, 1968; Pollock et al., 1970; Lippman et al., 1982; Olanoff and Fudenberg, 1983). Particular human leucocyte antigen (HLA) haplotypes are the strongest genetic determinants of many autoimmune diseases (Shoenfeld and Schwartz, 1984; Caillat-Zucman, 2009; Cho and Gregersen, 2011; Lessard et al., 2012), and warm AIHA is positively associated with HLA-DR15, with approximately 60% of the patients expressing this allele (Stott et al., 2002). Genome-wide association studies of other human autoimmune diseases reveal that large numbers of non-HLA genes further contribute to susceptibility (Cho and Gregersen, 2011; Lessard et al., 2012), and predisposition of the NZB mouse to AIHA has also been attributed to multiple loci (Chused et al., 1987; Lee et al., 2004; Scatizzi et al., 2012). The molecular bases of most such associations remain unknown. However, in common with other autoimmune-prone strains, the NZB mouse shares a promoter haplotype that is associated with reduced expression and function of the inhibitory FcγR FcγRIIb (Pritchard et al., 2000). The effects of the polymorphism on FcγRIIb expressed by macrophages and B cells are enhanced phagocytosis of IgGopsonized RBC and increased antibody responsiveness (Pritchard et al., 2000; Kikuchi et al., 2006).

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

904

47. AUTOIMMUNE HEMOLYTIC ANEMIA

Gender and Age Unlike most other human autoimmune diseases (Talal and Ahmed, 1987), the incidence of AIHA is no higher in women than in men (Pirofsky, 1976; Sokol et al., 1981, 1992). AIHA becomes progressively more common with age (Sokol et al., 1981, 1992), perhaps reflecting defects in immune regulation (Tomer and Shoenfeld, 1988; Talor and Rose, 1991; Akbar and Fletcher, 2005).

Infectious Agents Infectious agents are commonly implicated in provoking autoimmune disease in susceptible individuals (Shoenfeld and Isenberg, 1989), with almost 10% of human AIHA patients reported to have concurrent bacterial or viral conditions (Sokol et al., 1981, 1992), and RBC autoantibodies induced in mice by LCMV (Coutelier et al., 1994). Cross-reactivity between bacterial lipopolysaccharide and the blood group antigen I has been proposed to explain the high incidence of transient CAS which follows human Mycoplasma pneumoniae infection (Costea et al., 1972). The potential for mimicry to induce warm AIHA is exemplified by the disease that develops in mice following repeated injections of RBC expressing cross-reactive antigens from a closely related species, the rat (Playfair and Marshall-Clarke, 1973; Barker et al., 1993a). Studies of NZB mice also suggest that cross-reactivity between a microbe and a self-epitope can focus a predisposition to autoimmunity onto a particular target, even when not a primary or sufficient cause of disease (Hall et al., 2007). A second mechanism linking infection and AIHA is the ability of innate microbial stimuli and the cytokines they induce to activate antigen-presenting cells (APC) and therefore to enhance the immunogenicity of RBC autoantigens (Elson et al., 1995; Coutelier et al., 2007). Changes to the cytokine milieu resulting from infection, particularly IFN-γ production, can also enhance RBC phagocytosis by modulating both the subclass of autoantibody and the activation of macrophages (Atkinson and Frank, 1974; Coutelier et al., 2007). Finally, particular infectious agents associated with AIHA, such as Epstein Barr virus, may directly infect and dysregulate immune cells (Bowman et al., 1974).

Drugs Immune-mediated hemolytic anemias are a rare side effect of many drugs, including the penicillins, but in most cases, the antibodies are not strictly autoreactive and only bind RBC in the presence of the drug (Garratty, 2010; Garratty and Arndt, 2014). However, other examples such as α-methyldopa can induce true RBC autoantibodies that may cause AIHA (Sokol et al., 1981), by perturbing immune regulation (Kirtland et al., 1980) or altering the antigenic structure of RBC (Owens et al., 1982).

Neoplasia Up to 22% of the human AIHA cases suffer from some form of concurrent neoplastic disease (Sokol et al., 1981, 1992). Many patients with CAS have a monoclonal RBC autoantibody associated with a clonal lymphoproliferative disorder (Silberstein et al., 1986), most frequently classified as lymphoplasmacytic lymphoma (Berentsen and Tjønnfjord, 2012). Warm AIHA and autoimmune thrombocytopenia are both closely associated with CLL. Over 10% of AIHA cases are also diagnosed with the condition (Sokol et al., 1992), and circulating leukocytes with an abnormal CLL-like phenotype can be detected in further 19% of the patients classified with apparent primary AIHA (Mittal et al., 2008). Conversely, up to 14% of CLL patients have AIHA or elevated levels of RBCbound autoantibody (Dearden et al., 2008). One model to explain this association is that the large numbers of the malignant CLL cells present in the spleen drive an autoimmune response to circulating cells by acting as aberrant APC (Hall et al., 2005).

IMMUNE MECHANISMS UNDERLYING LOSS OF SELF TOLERANCE IN WARM AUTOIMMUNE HEMOLYTIC ANEMIA The study of specific pathogenic responses to RBC autoantigens has enabled mechanisms underlying the loss of self-tolerance in warm AIHA to be characterized.

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

IMMUNE MECHANISMS UNDERLYING LOSS OF SELF TOLERANCE IN WARM AUTOIMMUNE HEMOLYTIC ANEMIA

905

B Cells and Tolerance Although RBC destruction is autoantibody mediated, it is not necessary to invoke a defect in B-cell repertoire selection to explain the loss of tolerance in AIHA. Central tolerance of self-reactive B cells is incomplete in healthy individuals, since anti-RBC autoantibodies with a wide range of specificities can be induced to cause AIHA in murine strains that have no predisposition to spontaneous disease (Day et al., 1989; Barker et al., 1993a). Nevertheless, one model of AIHA, created by transgenic expression of an anti-RBC monoclonal autoantibody from NZB mice, does illustrate the potential for pathology to result from failure to censor autoreactive B cells (Murakami et al., 1992). The B cells producing monoclonal antibody are sequestered in the peritoneal cavity and survive to cause disease in only a proportion of mice, depending on whether they are deleted by contact with RBC (Murakami et al., 1992).

T-Helper Cells and Tolerance There is a long-standing belief that self-tolerance in the T-cell compartment is less secure than for B cells, and that, in health, antibody-mediated diseases such as AIHA are prevented due to lack of effective help (Naysmith et al., 1981; Elson and Barker, 2000). The vast majority of IgG responses are T dependent (Kelsoe, 1995), and the production of warm autoantibodies in AIHA appears to be no exception (Elson and Barker, 2000). NZB IgG autoantibody production in vivo is retarded by treatment with anti-CD4 monoclonal antibody (Oliveira et al., 1994), or by CD4 gene deletion (Chen et al., 1996), and splenic T-helper (Th) cells from NZB mice but not MHC-matched healthy strains, proliferate in vitro in response to the major murine RBC autoantigen, Band 3 (Perry et al., 1996; Shen et al., 1996). Furthermore, NZB disease is accelerated by immunization with an insoluble peptide bearing the dominant Th-cell epitope from Band 3 and ameliorated by mucosal administration of a soluble analog of this sequence (Shen et al., 2003). Other murine models are also Th dependent, since anti-CD4 mAb-treated mice do not develop AIHA induced by LCMV (Coutelier et al., 1994), and T-cell depletion prevents RBC autoantibody production in response to immunization with cross-reactive rat antigens (Naysmith et al., 1981). Findings in human AIHA are also consistent with the need for help. Rh autoantigen specific effector Th cells that have been activated in vivo can be demonstrated in the peripheral blood and/or spleen from all patients with anti-Rh autoantibodies (Barker et al., 1997), but from very few healthy donors (Barker and Elson, 1994; Barker et al., 1997). Warm AIHA in patients and NZB mice is associated with specific helper responses that are dominated by the Th1 subset, and inducing a corresponding Th2 bias can prevent or ameliorate NZB disease (Shen et al., 1996, 2003; Hall et al., 2002). Such a shift may be therapeutically beneficial partly because of the associated switch of the autoantibody to a less pathogenic isotype. Recent studies of human AIHA reveal that disease is also strongly associated with IL-17 responses to RBC, raising the possibility that Th17 cells may also provide help for autoreactive B cells to produce pathogenic IgG subclasses (Hall et al., 2012). In common with B cells, it appears that potentially autoaggressive T cells can escape central tolerance as part of normal immune development and that failure of peripheral mechanisms to control their activation results in AIHA. Healthy mice (Naysmith et al., 1981; Barker et al., 1993a, 2002), dogs (Corato et al., 1997), and humans (Barker and Elson, 1994) all harbor naı¨ve Th cells that can be stimulated to proliferate in vitro by RBC autoantigens. Comparison with AIHA patients demonstrates that they differ, not in the presence or fine specificity of circulating RBC-specific autoreactive Th cells but in the finding that these lymphocytes are activated in vivo (Barker and Elson, 1994; Barker et al., 1997). One possibility is that the surviving autoreactive Th cells are specific for RBC self-epitopes that are normally inefficiently processed and presented by APC from the intact antigen (Elson et al., 1995) and therefore unavailable to induce tolerance in the thymus. This model is supported by studies of human AIHA, where activated Th cells are specific for epitopes on the Rh protein autoantigens that are “cryptic” or subdominant (Hall et al., 1999). Such epitopes may be more efficiently presented and drive an autoaggressive Th response if APC are activated, for example, by infection (Elson et al., 1995) or by the accumulation of aberrant APC types such as CLL cells (Hall et al., 2005). The importance of antigen presentation is also illustrated by observations that the immunogenicity of RBC can be increased by changes in their innate receptor recognition by dendritic cells (Yi et al., 2015). It is now recognized that CD41 regulatory T (Treg) cells are important mediators of peripheral self-tolerance (Roncarolo et al., 2006; Sakaguchi et al., 2010; Shevach, 2011). AIHA induced by rat RBC immunization of mice provided an early example of such “infectious tolerance,” since the autoimmune response is transient and the mice become refractory to further induction of disease, with splenocytes transferred from recovered animals

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

906

47. AUTOIMMUNE HEMOLYTIC ANEMIA

providing protection to naı¨ve recipients (Playfair and Marshall-Clarke, 1973; Naysmith et al., 1981). Both the “adaptive” IL-101 (Roncarolo et al., 2006) and “natural” CD251FoxP31 (Sakaguchi et al., 2010; Shevach, 2011) forms of Treg cell have been implicated in maintaining or restoring tolerance to RBC autoantigens. In murine AIHA induced by rat RBC, recovery is associated with protective CD251 T cells (Mqadmi et al., 2005) and the development of AIHA in gene-deleted mice that lack IL-2 has been attributed to a deficiency of the “natural” Treg population (Hoyer et al., 2009). Treg cells specific for the target Rh autoantigens can be found in the peripheral blood or spleen of patients with AIHA and are capable of inhibiting the Th1 effector responses in vitro by secretion of IL-10 (Hall et al., 2002). The Rh-specific Treg cells have been cloned and shown to mediate inhibitory activity only after stimulation by cognate antigen, and not in response to polyclonal activators, illustrating the importance of specificity in their function (Ward et al., 2008). Although able to secrete the “adaptive” inhibitory cytokine IL-10, these Treg cells also express the “natural” marker FoxP3, and the Th1 transcription factor T-bet, revealing plasticity between the different regulatory forms and effector subsets (Ward et al., 2008).

CONCLUDING REMARKS In AIHA, many of the pathogenetic mechanisms by which autoantibodies can cause disease have been defined. The identification of major human and murine RBC autoantigens has also provided unique insights into the control of specific, pathogenic immune responses in both human and experimental animal disease. This work to understand how immunological tolerance is lost and can be restored holds out the prospect of more effective, specific therapies.

References Akbar, A.N., Fletcher, J.M., 2005. Memory T cell homeostasis and senescence during aging. Curr. Opin. Immunol. 17, 480 485. Alderman, E.M., Fudenberg, H.H., Lovins, R.E., 1981. Isolation and characterization of an age-related antigen present on senescent human red blood cells. Blood 58, 341 349. Atkinson, J.P., Frank, M.M., 1974. The effect of Bacillus Calmette-Gue´rin-induced macrophage activation on the in vivo clearance of sensitized erythrocytes. J. Clin. Invest. 53, 1742 1749. Avent, N.D., Reid, M.E., 2000. The Rh blood group system: a review. Blood 95, 375 387. Ballas, S.K., 1989. Spectrin autoantibodies in normal human serum and in polyclonal blood grouping sera. Br. J. Haematol. 71, 137 139. Barker, R.N., Elson, C.J., 1994. Multiple self-epitopes on the Rhesus polypeptides stimulate immunologically ignorant human T-cells in vitro. Eur. J. Immunol. 2, 1578 1582. Barker, R.N., Gruffydd-Jones, T.J., Stokes, C.R., Elson, C.J., 1991. Identification of autoantigens in canine autoimmune haemolytic anaemia. Clin. Exp. Immunol. 85, 33 40. Barker, R.N., Casswell, K.M., Reid, M.E., Sokol, R.J., Elson, C.J., 1992a. Identification of autoantigens in autoimmune haemolytic anaemia by a non-radioisotope immunoprecipitation method. Br. J. Haematol. 8, 126 132. Barker, R.N., Gruffydd-Jones, T.J., Stokes, C.R., Elson, C.J., 1992b. Autoimmune haemolysis in the dog: relationship between anaemia and the levels of red blood cell immunoglobulins and complement measured by an enzyme-linked antiglobulin test. Vet. Immunol. Immunopathol. 3, 1 20. Barker, R.N., Casswell, K.M., Elson, C.J., 1993a. Identification of murine erythrocyte autoantigens and cross-reactive rat antigens. Immunology 78, 568 573. Barker, R.N., De Sa´ Oliveira, G.G., Elson, C.J., Lydyard, P.M., 1993b. Pathogenic autoantibodies in the NZB mouse are specific for erythrocyte Band 3 protein. Eur. J. Immunol. 23, 1723 1726. Barker, R.N., Hall, A.M., Standen, G.R., Jones, J., Elson, C.J., 1997. Identification of T-cell epitopes on the Rhesus polypeptides in autoimmune hemolytic anemia. Blood 90, 2701 2715. Barker, R.N., Leader, K.A., Elson, C.J., 1999a. Serial changes in the galactosylation of autoantibody and serum IgG in autoimmune haemolytic anaemia. Autoimmunity 31, 103 108. Barker, R.N., Young, R.D., Leader, K.A., Elson, C.J., 1999b. Galactosylation of serum IgG and autoantibodies in murine models of autoimmune haemolytic anaemia. Clin. Exp. Immunol. 117, 449 454. Barker, R.N., Shen, C.-R., Elson, C.J., 2002. T-cell specificity in murine autoimmune haemolytic anaemia induced by rat red blood cells. Clin. Exp. Immunol. 129, 208 213. Barker, R.N., Vickers, M.A., Ward, F.J., 2007. Controlling autoimmunity—lessons from the study of red blood cells as model antigens. Immunol. Lett. 108, 20 26. Baudino, L., da Silveira, S.A., Nakata, M., Izui, S., 2006. Molecular and cellular basis for pathogenicity of autoantibodies, lessons from murine monoclonal autoantibodies. Springer Semin. Immunopathol. 28, 175 184. Baudino, L., Fossati-Jimack, L., Chevalley, C., Martinez-Soria, E., Shulman, M.J., Izui, S., 2007. IgM and IgA anti-erythrocyte autoantibodies induce anemia in a mouse model through multivalency-dependent hemagglutination but not through complement activation. Blood 109, 5355 5362.

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

REFERENCES

907

Baudino, L., Nimmerjahn, F., da Silveira, S.A., Martinez-Soria, E., Saito, T., Carroll, M., et al., 2008. Differential contribution of three activating IgG Fc receptors (FcgammaRI, FcgammaRIII, and FcgammaRIV) to IgG2a- and IgG2b-induced autoimmune hemolytic anemia in mice. J. Immunol. 180, 1948 1953. Baxter, A.G., Mandel, T.E., 1991. Hemolytic anemia in non-obese diabetic mice. Eur. J. Immunol. 21, 2051 2055. Berentsen, S., Tjønnfjord, G.E., 2012. Diagnosis and treatment of cold agglutinin mediated autoimmune hemolytic anemia. Blood. Rev. 26, 107 115. Berentsen, S., Ulvestad, E., Gjertsen, B.T., Hjorth-Hansen, H., Langholm, R., Knutsen, H., et al., 2004. Rituximab for primary chronic cold agglutinin disease, a prospective study of 37 courses of therapy in 27 patients. Blood 103, 2925 2928. Berentsen, S., Ulvestad, E., Langholm, R., Beiske, K., Hjorth-Hansen, H., Ghanima, W., et al., 2006. Primary chronic cold agglutinin disease, a population based clinical study of 86 patients. Haematologica 91, 460 466. Boorman, K.E., Dodd, B.E., Loutit, J.F., 1946. Haemolytic icterus (acholuric jaundice), congenital and acquired. Lancet 1, 812 814. Bowman, H.S., Marsh, W.L., Schumacher, H.R., Oyen, R., Reihart, J., 1974. Auto anti-N immunohemolytic anemia in infectious mononucleosis. Am. J. Clin. Pathol. 61, 465 472. Caillat-Zucman, S., 2009. Molecular mechanisms of HLA association with autoimmune diseases. Tissue Antigens 73, 1 8. Chaplin Jr., H., 1990. Red cell-bound immunoglobulin as a predictor of severity of hemolysis in patients with autoimmune hemolytic anemia. Transfusion 30, 576 578. Chen, S., Takeoka, Y., Ansari, A.A., Boyd, R., Klinman, D.M., Gershwin, M.E., 1996. The natural history of disease expression in CD4 and CD8 gene-deleted New Zealand Black (NZB) mice. J. Immunol. 157, 2676 2684. Cho, J.H., Gregersen, P.K., 2011. Genomics and the multifactorial nature of human autoimmune disease. N. Engl. J. Med. 365, 1612 1623. Chused, T.M., McCoy, K.L., Lal, R.B., Brown, E.M., Baker, P.J., 1987. Multigenic basis of autoimmune disease in New Zealand mice. Concepts Immunopathol. 4, 129 143. Clark, D.A., Dessypris, E.N., Jenkins Jr., D.E., Krantz, S.B., 1984. Acquired immune hemolytic anemia associated with IgA erythrocyte coating, investigation of hemolytic mechanisms. Blood 64, 1000 1005. Conley, C.L., Lippman, S.M., Ness, P.M., Petz, L.D., Branch, D.R., Gallagher, M.T., 1982. Autoimmune hemolytic anemia with reticulocytopenia and erythroid marrow. N. Engl. J. Med. 306, 281 286. Coombs, R.R.A., Mourant, A.E., Race, R.R., 1945. A new test for the detection of weak and “incomplete” Rh agglutinins. Br. J. Exp. Pathol 26, 255 266. Corato, A., Shen, C.-R., Mazza, G., Barker, R.N., Day, M.J., 1997. Proliferative responses of peripheral blood mononuclear cells from normal dogs and dogs with autoimmune haemolytic anaemia to red blood cell antigens. Vet. Immunol. Immunopathol. 59, 191 204. Cordova, M.S., Baez-Villasenor, J., Mendez, J.J., Campos, E., 1966. Acquired hemolytic anemia with positive antiglobulin (Coombs’) test in mother and daughter. Arch. Intern. Med. 117, 692 695. Costea, N., Yakulis, V.J., Heller, P., 1972. Inhibition of cold agglutinins (anti-I) by M. pneumoniae antigens. Proc. Soc. Exp. Biol. Med. 139, 476 479. Coutelier, J.-P., Johnston, S.J., El Idrissi, M. el-A., Pfau, C.J., 1994. Involvement of CD4 1 cells in lymphocytic choriomeningitis virus-induced autoimmune anemia and hypergammaglobulinemia. J. Autoimmun 7, 589 599. Coutelier, J.-P., Detalle, L., Musaji, A., Meite, M., Izui, S., 2007. Two-step mechanism of virus-induced autoimmune hemolytic anemia. Ann. N. Y. Acad. Sci. 1109, 151 157. Crosby, W.H., Rappaport, H., 1956. Reticulocytopenia in autoimmune hemolytic anemia. Blood 11, 926 936. Crowther, M., Chan, Y.L., Garbett, I.K., Lim, W., Vickers, M.A., Crowther, M.A., 2011. Evidence-based focused review of the treatment of idiopathic warm immune hemolytic anemia in adults. Blood 118, 4036 4040. da Silveira, S.A., Kikuchi, S., Fossati-Jimack, L., Moll, T., Saito, T., Verbeek, J.S., et al., 2002. Complement activation selectively potentiates the pathogenicity of the IgG2b and IgG3 isotypes of a high affinity anti-erythrocyte autoantibody. J. Exp. Med. 195, 665 672. Dausset, J., Colombani, J., 1959. The serology and prognosis of 128 cases of autoimmune hemolytic anemia. Blood 14, 1280 1301. Day, M.J., Russell, J., Kitwood, A.J., Ponsford, M., Elson, C.J., 1989. Expression and regulation of erythrocyte auto-antibodies in mice following immunization with rat erythrocytes. Eur. J. Immunol. 19, 795 801. de Sa´ Oliveira, G.G., Izui, S., Ravirajan, C.T., Mageed, R.A.K., Lydyard, P.M., Elson, C.J., et al., 1996. Diverse antigen specificity of erythrocytereactive monoclonal autoantibodies from NZB mice. Clin. Exp. Immunol. 10, 313 320. Dearden, C., Wade, R., Else, M., Richards, S., Milligan, D., Hamblin, T., et al., 2008. The prognostic significance of a positive direct antiglobulin test in chronic lymphocytic leukemia, a beneficial effect of the combination of fludarabine and cyclophosphamide on the incidence of hemolytic anemia. Blood 111, 1820 1826. Dellagi, K., Brouet, J.C., Schenmetzler, C., Praloran, V., 1981. Chronic hemolytic anemia due to a monoclonal IgG cold agglutinin with anti-Pr specificity. Blood 57, 189 191. Dierickx, D., Kentos, A., Delannoy, A., 2015. The role of rituximab in adults with warm antibody autoimmune hemolytic anemia. Blood 125, 3223 3229. Dixon, P.M., Matthews, A.G., Brown, R., Millar, P.M., Ritchie, J.S.D., 1978. Bovine auto-immune haemolytic anaemia. Vet. Rec. 103, 155 157. ¨ ber paroxysmale Ha¨moglobinurie. Munch. Med. Wochenschr. 51, 1590 1593. Donath, J., Landsteiner, K., 1904. U Elson, C.J., Barker, R.N., 2000. Helper T cells in antibody-mediated, organ specific autoimmunity. Curr. Opin. Immunol. 12, 664 669. Elson, C.J., Barker, R.N., Thompson, S.J., Williams, N.A., 1995. Immunologically ignorant T-cells, epitope spreading and repertoire limitation. Immunol. Today 1, 71 76. Engelfriet, C.P., Von dem Borne, A.E.G.Kr, Beckers, D., Van der Meulen, F.W., Fleer, A., Roos, D., et al., 1981. Immune destruction of red cells. Seminar on Immune Mediated Cell Destruction. American Association of Blood Banks, Washington DC, pp. 93 130. Fossati-Jimack, L., Reininger, L., Chicheportiche, Y., Clynes, R., Ravetch, J.V., Honjo, T., et al., 1999. High pathogenic potential of low-affinity autoantibodies in experimental autoimmune hemolytic anemia. J. Exp. Med. 190, 1689 1696. Fox, R.R., Meier, H., Crary, D.D., Norberg, R.F., Myers, D.D., 1971. Hemolytic anemia associated with thymoma in the rabbit. Genetic studies and pathological findings. Oncology 25, 372 382.

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

908

47. AUTOIMMUNE HEMOLYTIC ANEMIA

Frank, M.M., Hamburger, M.I., Lawley, T.J., Kimberley, R.P., Plotz, P.H., 1979. Defective reticuloendothelial system Fc-receptor function in systemic lupus erythematosus. N. Eng. J. Med. 300, 518. Freedman, J., Ho, M., Barefoot, C., 1982. Red blood cell-bound C3d in selected hospital patients. Transfusion 22, 515 520. Freedman, J., Wright, J., Lim, F.C., Garvey, M.B., 1987. Hemolytic warm IgM autoagglutinins in autoimmune hemolytic anemia. Transfusion 27, 464 467. Fries, L.F., Brickman, C.M., Frank, M.M., 1983. Monocyte receptors for the Fc portion of IgG increase in number in autoimmune hemolytic anemia and other hemolytic states and are decreased by glucocorticoid therapy. J. Immunol. 131, 1240 1245. Garratty, G., 1983. Mechanisms of immune red cell destruction, and red cell compatibility testing. Hum. Pathol. 14, 204 212. Garratty, G., 1989. Factors affecting the pathogenicity of red cell autoantibodies and alloantibodies. In: Nance, S.J. (Ed.), Immune Destruction of Red Blood Cells. American Association of Blood Banks, Arlington, VA, pp. 109 169. Garratty, G., 1990. Predicting the clinical significance of red cell antibodies with in vitro cellular assays. Transfus. Med. Rev IV, 297 312. Garratty, G., 2010. Immune hemolytic anemia associated with drug therapy. Blood Rev. 24, 143 150. Garratty, G., Arndt, P.A., 2014. Drugs that have been shown to cause drug-induced immune hemolytic anemia or positive direct antiglobulin tests: some interesting findings since 2007. Immunohematology 30, 66 79. Garratty, G., Nance, S.J., 1990. Correlation between in vivo hemolysis and the amount of red cell-bound IgG measured by flow cytometry. Transfusion 30, 617 621. Griffiths, H.L., Kumpel, B.M., Elson, C.J., Hadley, A.G., 1994. The functional activity of human monocytes passively sensitized with monoclonal anti-D suggests a novel role for Fc gamma RI in the immune destruction of blood cells. Immunology 83, 370 377. Hadley, A.G., Zupanska, B., Kumpel, B.M., Pilkington, C., Griffiths, H.L., Leader, K.A., et al., 1995. The glycosylation of red cell autoantibodies affects their functional activity in vitro. Br. J. Haematol. 91, 587 594. Hall, A.M., Stott, L.-M., Wilson, D.W.L., Urbaniak, S.J., Barker, R.N., 1999. Different epitopes are targeted by helper T-cells responding to the same human protein as an autoantigen or foreign antigen. J. Autoimmun. 27, 80. Hall, A.M., Ward, F.J., Vickers, M.A., Stott, L.-M., Urbaniak, S.J., Barker, R.N., 2002. Interleukin-10 mediated regulatory T-cell responses to epitopes on a human red blood cell autoantigen. Blood 100, 4529 4536. Hall, A.M., Vickers, M.A., McLeod, E., Barker, R.N., 2005. Rh autoantigen presentation to helper T cells in chronic lymphocytic leukemia by malignant B-cells. Blood. 105, 2007 2015. Hall, A.M., Shen, C.-R., Ward, F.J., Rowe, C., Bowie, L., Devine, A., et al., 2007. Deletion of the dominant autoantigen in NZB mice with autoimmune hemolytic anemia: effects on autoantibody and T-helper responses. Blood 110, 4511 4517. Hall, A.M., Zamzami, O.M., Whibley, N., Hampsey, D.P., Haggart, A.M., Vickers, M.A., et al., 2012. Production of the effector cytokine interleukin-17, rather than interferon-γ, is more strongly associated with autoimmune hemolytic anemia. Hematologica 97, 1494 1500. Heddle, N.M., Kelton, J.G., Turchyn, K.L., Ali, M.A., 1988. Hypergammaglobulinemia can be associated with a positive direct antiglobulin test, a nonreactive eluate, and no evidence of hemolysis. Transfusion 28, 29 33. Helyer, B.J., Howie, J.B., 1963. Spontaneous auto-immune disease in NZB/B1 mice. Br. J. Haematol. 9, 119 131. Hernandez-Jodra, M., Hudnall, S.D., Petz, L.D., 1990. Studies of in vitro red cell autoantibody production in normal donors and in patients with autoimmune hemolytic anemia. Transfusion 30, 411 417. Hoyer, K.K., Kuswanto, W.F., Gallo, E., Abbas, A.K., 2009. Distinct roles of helper T-cell subsets in a systemic autoimmune disease. Blood 113, 389 395. Huh, Y.O., Liu, F.J., Rogge, K., Chakrabarty, L., Lichtiger, B., 1988. Positive direct antiglobulin test and high serum immunoglobulin G values. Am. J. Clin. Pathol. 90, 197 200. Jenkins, W.J., Marsh, W.J., Noades, J., Tippett, P., Sanger, R., Race, R.R., 1960. The I antigen and antibody. Vox Sang. 5, 97 121. Kaplan, A.V., Quimby, F.W., 1983. A radiolabelled staphylococcal protein A assay for detection of anti-erythrocyte IgG in warm agglutinin autoimmune hemolytic anemia in dogs and man. Vet. Immunol. Immunopathol. 4, 307 317. Kay, M.M., Marchalonis, J.J., Hughes, J., Watanabe, K., Schluter, S.F., 1990. Definition of a physiologic aging autoantigen by using synthetic peptides of membrane protein band 3: localization of the active antigenic sites. Proc. Natl. Acad. Sci. U.S.A 87, 5734 5738. Kelsoe, G., 1995. The germinal center reaction. Immunol. Today 16, 324 326. Kelton, J.G., 1985. Impaired reticuloendothelial function in patients treated with methyldopa. N. Engl. J. Med. 313, 596 600. Kelton, J.G., Singer, J., Rodger, C., Gauldie, J., Horsewood, P., Dent, P., 1985. The concentration of IgG in the serum is a major determinant of Fc-dependent reticuloendothelial function. Blood 66, 490 495. Kikuchi, S., Santiago-Raber, M.L., Amano, H., Amano, E., Fossati-Jimack, L., Moll, T., et al., 2006. Contribution of NZB autoimmunity 2 to Y-linked autoimmune acceleration-induced monocytosis in association with murine systemic lupus. J. Immunol. 176, 3240 3247. Kirtland, H.H., Mohler, D.N., Horwitz, D.A., 1980. Methyldopa inhibition of suppressor-lymphocyte function. A proposed cause of autoimmune hemolytic anemia. N. Engl. J. Med. 302, 825 832. Krych-Goldberg, M., Atkinson, J.P., 2001. Structure-function relationships of complement receptor type 1. Immunol. Rev 180, 112 122. Kurlander, R.J., Rosse, W.F., Logue, G.L., 1978. Quantitative influence of antibody and complement coating of red cells in monocyte-mediated cell lysis. J. Clin. Invest. 61, 1309 1319. Landsteiner, K., Levine, P., 1926. On the cold agglutinins in human serum. J. Immunol. 12, 441 460. Leddy, J.P., Falany, J.L., Kissel, G.E., Passador, S.T., Rosenfeld, S.I., 1993. Erythrocyte membrane proteins reactive with human (warm reacting) anti-red cell autoantibodies. J. Clin. Invest. 91, 1672 1680. Lee, N.J., Rigby, R.J., Gill, H., Boyle, J.J., Fossati-Jimack, L., Morley, B.J., et al., 2004. Multiple loci are linked with anti-red blood cell antibody production in NZB mice—comparison with other phenotypes implies complex modes of action. Clin. Exp. Immunol. 138, 39 46. Lefrere, J.-J., Courouce, A.-M., Bertrand, Y., Girot, R., Soulier, J.-P., 1986. Human parvovirus and aplastic crisis in chronic hemolytic anemias: a study of 24 observations. Am. J. Hematol. 23, 271 275. Lessard, C.J., Ice, J.A., Adrianto, I., Wiley, G.B., Kelly, J.A., Gaffney, P.M., et al., 2012. The genomics of autoimmune disease in the era of genome-wide association studies and beyond. Autoimmun. Rev. 11, 267 275.

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

REFERENCES

909

Liesveld, J.L., Rowe, J.M., Lichtman, M.A., 1987. Variability of the erythropoietic response in autoimmune hemolytic anemia. Analysis of 109 cases. Blood 69, 820 826. Lippman, S.M., Arnett, F.C., Conley, C.L., Ness, P.M., Meyers, D.A., Bias, W.B., 1982. Genetic factors predisposing to autoimmune diseases: autoimmune hemolytic anemia, chronic thrombocytopenic purpura and systemic lupus erythematosus. Am. J. Med. 73, 827 840. Loutit, J.F., Mollison, P.L., 1946. Haemolytic icterus (acholuric jaundice), congenital and acquired. J. Pathol. Bacteriol. 58, 711 728. Lutz, H.U., Wipf, G., 1982. Naturally occurring autoantibodies to skeletal proteins from human red blood cells. J. Immunol. 128, 1695 1699. Mair, T.S., Taylor, F.G.R., Hillyer, M.H., 1990. Autoimmune haemolytic anaemia in eight horses. Vet. Rec. 126, 51 53. Malhotra, R., Wormald, M.R., Rudd, P.M., Fischer, T.B., Dwek, R.A., Sims, R.B., 1995. Alterations in glycosylation of IgG associated with rheumatoid arthritis; activating complement via the mannose binding protein. Nat. Med. 1, 237 243. Marsh, W.L., Jenkins, W.J., 1960. Anti-i, a new cold antibody. Nature 188, 753. Mazza, G., el Idrissi, M.E., Coutelier, J.P., Corato, A., Elson, C.J., Pfau, C.J., et al., 1997. Infection of C3HeB/FeJ mice with the docile strain of lymphocytic choriomeningitis virus induces autoantibodies specific for erythrocyte Band 3. Immunology 91, 239 245. Mittal, S., Blaylock, M., Culligan, D.J., Barker, R.N., Vickers, M.A., 2008. A high rate of “CLL phenotype” lymphocytes in autoimmune hemolytic anemia and immune thrombocytopenic purpura. Haematologica 93, 151 152. Mollison, P.L., 1959. Measurement of survival and destruction of red cells in haemolytic syndromes. Br. Med. Bull. 15, 59 66. Mollison, P.L., Hughes-Jones, N.C., 1967. Clearance of Rh-positive red cells by low concentrations of Rh antibody. Immunology 12, 63 73. Mqadmi, A., Zheng, X., Yazdanbakhsh, K., 2005. CD4 1 CD25 1 regulatory T cells control induction of autoimmune hemolytic anemia. Blood 105, 3746 3748. Murakami, M., Tsubata, T., Okamoto, M., Shimizu, A., Kumagai, S., Imura, H., et al., 1992. Antigen-induced apoptotic death of Ly-1 B cells responsible for autoimmune disease in transgenic mice. Nature 357, 77 80. Naysmith, J.D., Ortega-Pierres, M.G., Elson, C.J., 1981. Rat erythrocyte induced anti-erythrocyte autoantibody production and control in normal mice. Immunol. Rev. 55, 55 87. Nicholson-Weller, A., Burge, J., Fearon, D.T., Weller, P.F., Austen, K.F., 1982. Isolation of a human erythrocyte membrane glycoprotein with decay accelerating activity for C3 convertases of the human complement system. J. Immunol. 129, 184 189. Nimmerjahn, F., Ravetch, J.V., 2008. Fcgamma receptors as regulators of immune responses. Nat. Rev. Immunol. 8, 34 47. Olanoff, L.S., Fudenberg, H.H., 1983. Familial autoimmunity. Twenty years later. J. Clin. Lab. Immunol. 11, 105 111. Oliveira, G.G., Hutchings, P.R., Roitt, I.M., Lydyard, P.M., 1994. Production of erythrocyte autoantibodies in NZB mice is inhibited by CD4 antibodies. Clin. Exp. Immunol. 96, 297 302. Owens, N.A., Hui, H.L., Green, F.A., 1982. Induction of direct Coombs positivity with alpha-methyldopa in chimpanzees. J. Med 13, 473 477. Packman, C.H., 2008. Hemolytic anemia due to warm autoantibodies. Blood Rev. 22, 17 31. Pantaleo, A., Giribaldi, G., Mannu, F., Arese, P., Turrini, F., 2008. Naturally occurring anti-Band 3 antibodies and red blood cell removal under physiological and pathological conditions. Autoimmun. Rev. 7, 457 462. Pen˜alver, F.J., Alvarez-Larra´n, A., Dı´ez-Martin, J.L., Gallur, L., Jarque, I., Caballero, D., et al., 2010. Multi-institutional retrospective study on the use of rituximab in refractory AIHA. Rituximab is an effective and safe therapeutic alternative in adults with refractory and severe autoimmune hemolytic anemia. Ann. Hematol. 89, 1073 1080. Perry, F.E., Barker, R.N., Mazza, G., Day, M.J., Wells, A.D., Shen, C.-R., et al., 1996. Autoreactive T-cell specificity in autoimmune hemolytic anemia of the NZB mouse. Eur. J. Immunol. 2, 136 141. Petz, L.D., 2008. Cold antibody autoimmune hemolytic anemias. Blood Rev. 22, 1 15. Petz, L.D., Garratty, G., 2004a. Classification and characteristics of autoimmune hemolytic anemias. In: Petz, L.D., Garratty, G. (Eds.), Immune Hemolytic Anemias, second ed Churchill Livingstone, Philadelphia, PA, pp. 61 131. Petz, L.D., Garratty, G., 2004b. Mechanisms of immune hemolysis. In: Petz, L.D., Garratty, G. (Eds.), Immune Hemolytic Anemias, second ed Churchill Livingstone, Philadelphia, PA, pp. 133 165. Pirofsky, B., 1968. Hereditary aspects of autoimmune hemolytic anemia. A retrospective analysis. Vox Sang. 14, 334 347. Pirofsky, B., 1976. Clinical aspects of autoimmune hemolytic anemia. Semin. Hematol. 13, 251 265. Playfair, J.H.L., Marshall-Clarke, S., 1973. Induction of red cell autoantibodies in normal mice. Nat. New Biol. 243, 213 214. Pollock, J.G., Fenton, E., Barrett, K.E., 1970. Familial autoimmune haemolytic anaemia associated with rheumatoid arthritis and pernicious anaemia. Br. J. Haematol. 18, 171 182. Pritchard, N.R., Cutler, A.J., Uribe, S., Chadban, S.J., Morley, B.J., Smith, K.G., 2000. Autoimmune-prone mice share a promoter haplotype associated with reduced expression and function of the Fc receptor FcgammaRII. Curr. Biol. 10, 227 230. Roncarolo, M.G., Gregori, S., Battaglia, M., Bacchetta, R., Fleischhauer, K., Levings, M.K., 2006. Interleukin-10-secreting type 1 regulatory T cells in rodents and humans. Immunol. Rev. 212, 28 50. Ross, G.D., Medof, M.E., 1985. Membrane complement receptors specific for bound fragments of C3. Adv. Immunol. 37, 217 267. Rosse, W.F., 1971. Quantitative immunology of immune hemolytic anemia. II. The relationship of cell-bound antibody to hemolysis and the effect of treatment. J. Clin. Invest. 50, 734 743. Ruiz-Argu¨elles, A., Llorente, L., 2007. The role of complement regulatory proteins (CD55 and CD59) in the pathogenesis of autoimmune hemocytopenias. Autoimmun. Rev. 6, 155 161. Sakaguchi, S., Miyara, M., Costantino, C.M., Hafler, D.A., 2010. FOXP3 1 regulatory T cells in the human immune system. Nat. Rev. Immunol. 10, 490 500. Scatizzi, J.C., Haraldsson, M.K., Pollard, K.M., Theofilopoulos, A.N., Kono, D.H., 2012. The Lbw2 locus promotes autoimmune hemolytic anemia. J. Immunol. 188, 3307 3314. Shen, C.-R., Mazza, G., Perry, F.E., Beech, J.T., Thompson, S.J., Corato, A., et al., 1996. T-helper 1 dominated responses to erythrocyte Band 3 in NZB mice. Immunology 8, 195 199. Shen, C.-R., Youssef, A.-R., Devine, A., Bowie, L., Hall, A.M., Wraith, D.C., et al., 2003. Peptides containing a dominant T-cell epitope from red cell Band 3 have in vivo immunomodulatory properties in NZB mice with autoimmune hemolytic anemia. Blood 102, 3800 3806.

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES

910

47. AUTOIMMUNE HEMOLYTIC ANEMIA

Shevach, E.M., 2011. Biological functions of regulatory T cells. Adv. Immunol. 112, 137 176. Shoenfeld, Y., Schwartz, R.S., 1984. Immunologic and genetic factors in autoimmune diseases. N. Engl. J. Med. 311, 1019 1029. Shoenfeld, Y., Isenberg, D.A., 1989. The mosaic of autoimmunity. Immunol. Today 10, 123 126. Silberstein, L.E., Robertson, G.A., Harris, A.C., Moreau, L., Besa, E., Nowell, P.C., 1986. Etiologic aspects of cold agglutinin disease, Evidence for cytogenetically defined clones of lymphoid cells and the demonstration that an anti-Pr cold autoantibody is derived from a chromosomally aberrant B cell clone. Blood 67, 1705 1709. Sokol, R.J., Hewitt, S., 1985. Autoimmune hemolysis. A critical review. CRC Crit. Rev. Oncol. Hematol. 4, 125 154. Sokol, R.J., Hewitt, S., Stamps, B.K., 1981. Autoimmune haemolysis: an 18-year study of 865 cases referred to a regional transfusion centre. Br. Med. J. 282, 2023 2027. Sokol, R.J., Hewitt, S., Stamps, B.K., 1982. Autoimmune haemolysis associated with Donath-Landsteiner antibodies. Acta Haemat. 68, 268 277. Sokol, R.J., Hewitt, S., Stamps, B.K., 1983. Autoimmune haemolysis. Mixed warm and cold antibody type. Acta Haemat. 69, 266 274. Sokol, R.J., Hewitt, S., Stamps, B.K., Hitchen, P.A., 1984. Autoimmune haemolysis in childhood and adolescence. Acta Haemat. 72, 245 257. Sokol, R.J., Hewitt, S., Booker, D.J., Stamps, R., 1985. Enzyme linked direct antiglobulin tests in patients with autoimmune haemolysis, J. Clin. Pathol. 38, 912 914. Sokol, R.J., Hewitt, S., Booker, D.J., Stamps, R., Booth, J.R., 1988. An enzyme-linked direct antiglobulin test for assessing erythrocyte bound immunoglobulins, J. Immunol. Meth. 106, 31 35. Sokol, R.J., Hewitt, S., Booker, D.J., Bailey, A., 1990a. Erythrocyte autoantibodies, subclasses of IgG and autoimmune haemolysis. Autoimmunity, 6, 99 104. Sokol, R.J., Hewitt, S., Booker, D.J., Bailey, A., 1990b. Erythrocyte autoantibodies, multiple immunoglobulin classes and autoimmune haemolysis. Transfusion, 30, 714 717 Sokol, R.J., Booker, D.J., Stamps, R., 1992. The pathology of autoimmune haemolytic anaemia, J. Clin. Pathol. 45, 1047 1052. Sokol, R.J., Booker, D.J., Stamps, R., 1999. Erythropoiesis: paroxysmal cold haemoglobinuria, a clinico-pathological study of patients with a positive Donath-Landsteiner test. Hematology, 4, 137 164. Stott, L.-M., Urbaniak, S.J., Barker, R.N., 2002. Specific production of regulatory T-cell cytokines, responsiveness to the RhD blood group, and expression of HLA-DRB1 15. Immunology 107, 6. Switzer, J.W., Jain, N.C., 1981. Autoimmune hemolytic anemia in dogs and cats. Vet. Clin. North Am. Small Anim. Pract. 11, 405 420. Talal, N., Ahmed, S.A., 1987. Immunomodulation by hormones—an area of growing importance. J. Rheumatol. 14, 191 193. Talor, E., Rose, N.R., 1991. Hypothesis. The aging paradox and autoimmune disease. Autoimmunity 8, 245 249. Tomer, Y., Shoenfeld, Y., 1988. Ageing and autoantibodies. Autoimmunity 1, 141 149. Urbaniak, S.J., Griess, M.A., 1980. ADCC (K-cell) lysis of human erythrocytes sensitized with Rhesus alloantibodies. III. Comparison of IgG anti-D agglutinating and lytic (ADCC) activity and the role of IgG subclasses. Br. J. Haematol. 46, 447 453. Van der Meulen, F.W., De Bruin, H.G., Goosen, P.C.M., Bruynes, E.C.E., Joustra-Maas, C.J., Telkamp, H.G., et al., 1980. Quantitative aspects of the destruction of red cells sensitized with IgG1 autoantibodies. An application of flow cytometry. Br. J. Haematol. 46, 47 56. Victoria, E.J., Pierce, S.W., Branks, M.J., Masouredis, S.P., 1990. IgG red blood cell autoantibodies in autoimmune hemolytic anemia bind to epitopes on red blood cell membrane band 3 glycoprotein. J. Lab. Clin. Med. 115, 74 88. Ward, F.J., Hall, A.M., Cairns, L.S., Leggat, A.S., Urbaniak, S.J., Vickers, M.A., et al., 2008. Clonal regulatory T cells specific for a red blood cell autoantigen in human autoimmune hemolytic anemia. Blood 111, 680 687. Weiner, W., Vos, G.H., 1963. Serology of acquired hemolytic anemias. Blood 22, 606 613. Wiener, E., Hughes-Jones, N.C., Irish, W.T., Wickramasinghe, S.N., 1986. Elution of antispectrin antibodies from red cells in homozygous β-thalassaemia. Clin. Exp. Immunol. 63, 680 686. Win, N., Islam, S.I., Peterkin, M.A., Walker, I.D., 1997. Positive direct antiglobulin test due to antiphospholipid antibodies in normal healthy blood donors. Vox Sang. 72, 182 184. Yi, T., Li, J., Chen, H., Wu, J., An, J., Xu, Y., et al., 2015. Splenic dendritic cells survey red blood cells for missing self-CD47 to trigger adaptive immune responses. Immunity 43, 764 775. Youssef, A.R., Shen, C.-R., Lin, C.-L., Barker, R.N., Elson, C.J., 2005. IL-4 and IL-10 modulate autoimmune haemolytic anaemia in NZB mice. Clin. Exp. Immunol. 139, 84 89. Zanella, A., Barcellini, W., 2014. Treatment of autoimmune hemolytic anemias. Haematologica 99, 1547 1554. Zecca, M., Nobili, B., Ramenghi, U., Perrotta, S., Amendola, G., Rosito, P., et al., 2003. Rituximab for the treatment of refractory autoimmune hemolytic anemia in children. Blood 101, 3857 3861.

VII. ORGAN SPECIFIC AUTOIMMUNE DISEASES