Hemolytic Transfusion Reactions: Acute and Delayed

ii. Noninfectious Complications Chapter 49

Hemolytic Transfusion Reactions: Acute and Delayed R. Sue Shirey

●

Karen E. King

●

Paul M. Ness

ACUTE HEMOLYTIC TRANSFUSION REACTIONS

III 668

The most feared adverse reaction to blood transfusion is an acute hemolytic transfusion reaction (AHTR). These reactions most commonly occur when red cells (RBCs) are transfused to a patient with a preexisting antibody that is capable of destroying incompatible RBCs through intravascular hemolysis. These reactions can produce hypotension and shock, often accompanied by acute renal failure and disseminated intravascular coagulation (DIC), and have a high mortality rate. Because of the devastating nature of the most severe cases of AHTR, blood centers and transfusion services have developed standard operating procedures to avoid these consequences. Clinicians are taught to be suspicious of AHTRs and to initiate treatment rapidly in the hope of preventing the many complications and sequelae.

Definition and Incidence An AHTR features rapid destruction of RBCs immediately after a transfusion, but a hemolytic reaction occurring within 24 hours of the inciting transfusion is generally considered to be an AHTR.1 AHTRs produce serologic abnormalities and clinical events, but most reports do not distinguish how the cases were identified, and the literature has not developed a consensus case definition. Most reported reactions occur with RBCs, but AHTR reactions due to RBC antibodies contained in the plasma of other blood components (platelets or plasma-derived products) have historically and more recently been recognized as producing AHTRs.2 The incidence of AHTR in clinical practice has never been precisely determined. Historic studies have estimated their occurrence to be from 1 in 10,000 to 1 in 50,000 transfused blood components.3,4 Other information has been gleaned from reports to the Food and Drug Administration (FDA) on transfusion fatalities, but these numbers clearly misrepresent the totality of AHTR reactions.5,6 Any transfusion-medicine veteran knows of many cases or near misses from quality assurance activities or medical/legal cases that are never reported. The growing use of hemovigilance reporting around the world may provide better data in the future. As an example, a report from Canada documented 11 cases of AHTR from 138,605 units of RBC administered in

Ch49-F039816.indd 668

2000.7 Because these reactions occurred in hospitals where transfusion safety officers were already in place, it is likely that the incidence is higher in sites where hemovigilance activities have not been initiated. It is logical that reaction severity will correlate with the amount of incompatible blood that is administered. Published reports document death rates of 25% when less than 1 L of RBCs was given, with mortality increasing to 44% when infusions of greater than 1 L were transfused.8 Conversely, small aliquots of blood have caused major reactions,6 and whole units of RBCs that were ABO incompatible caused no sequelae.

Pathophysiology Transfusion of RBCs that are incompatible with antibodies in the patient’s plasma most commonly initiates AHTR. Less commonly, antibodies can be transfused from the donor that will destroy the patient’s incompatible RBCs. The antibodies that cause AHTR are most commonly within the ABO system, where high-titer naturally occurring antibodies react with the dense ABO antigen sites on RBCs, producing hemolysis. Anti-A is the most common culprit, because it has a higher titer in most group O individuals, and transfusion errors involving administration of group A blood to group O individuals are statistically most probable. Although ABO antibodies account for the majority of fatal cases of AHTR, other antibodies in the Kell, Rh, Kidd, and Duffy systems can be equally severe in some cases.3 The initiating events of an AHTR involve the binding of antibody to incompatible RBCs and the subsequent destruction of the RBCs by intravascular hemolysis. These events activate the complement system, the release of hemoglobin from the RBCs, and the presence of residual RBC stroma in the circulation. Although AHTR is typically considered a classic example of intravascular hemolysis, most likely some elements of extravascular hemolysis occur as well with clearance of some damaged red cells by the reticuloendothelial system. Immune hemolysis with complement activation generates the major complications of AHTR through a series of activated complement components, anaphylotoxins, and other immune mediators such as cytokines and vasoactive amines.1 These events cause hypotension, vasoconstriction and renal ischemia, and the activation of the coagulation

9/22/06 8:46:25 AM

Clinical Picture No consistent clinical picture of AHTR exists, with reactions being described in all settings where transfusion therapy is being administered. Most commonly, an alert patient might complain of chills, and the vital signs that are monitored with transfusion therapy will detect hypotension and fever. Pain at the infusion site, flank pain, a general feeling of being unwell, and anxiety with a feeling of impending doom have also been described. In patients who are unconscious or in surgery, vital-sign changes and the onset of unexplained bleeding due to DIC or the observation of hemoglobinuria in catheterized patients may be the only warning. Because the presentation of AHTR is nonspecific, it is critical that all patients undergoing transfusion therapy be closely observed with careful monitoring of vital signs and that any untoward complication be evaluated immediately as a suspected transfusion reaction. A list of common signs and symptoms of AHTR is found in Table 49–1, although the list is by no means exhaustive.

Ch49-F039816.indd 669

HEMOLYTIC TRANSFUSION REACTIONS

system of platelets and clotting factors. When complement is fully activated and RBC stroma and enzymes are released into the vascular space, hypotension results from the actions of anaphylotoxins and mast cell degranulation, with release of histamine and serotonin. Hypotension and renal failure are also facilitated by the activity of cytokines and interleukins produced as a result of immune hemolysis.9 The kallikrein system and bradykinin are also activated, causing vasodilation with increased capillary permeability, adding to the clinical picture of shock with renal failure, along with elements of adult respiratory distress syndrome.10 The massive release of proinflammatory molecules such as tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-8 activate neutrophils and monocytes, enhancing the clinical picture of shock, renal failure, and pulmonary compromise.11,12 These catastrophic events have profound effects on platelets and the coagulation system as well. Platelets are activated by the immune hemolytic reaction, releasing additional serotonin and histamine, which furthers the vasoconstrictive events. Platelet phospholipid (platelet factor 3) is also released, with procoagulant effects on coagulation.13,14 As a result, the intrinsic coagulation system is activated with the presence of bioactive thrombin, the consumption of fibrinogen, and the initiation of fibrinolysis. These procoagulant forces produce microthrombi, exacerbating renal damage, and diminished platelets and coagulation factors in many patients produce the clinical picture of DIC and hemostatic compromise. Most of the evolving picture of the pathophysiology of AHTR has been extracted from clinical case reports and descriptions. Much of this picture was well described in an early review by Goldfinger15 in 1977. This seminal review was updated with a more comprehensive picture of the implications of the systemic inflammatory response in AHTR later by Capon and Goldfinger16 formulating a model for the consideration of therapy. The pathophysiology of AHTR has also been studied in animals in recent years by Davenport,12,13 with the identification of important clinical roles of immune mediators such as IL-1 and monocyte chemoattractant protein. We hope that animal models will provide insights into potential therapies because clinical trials of newer agents will be difficult to perform in the sporadic cases that occur in multiple locations.

Table 49–1 Signs and Symptoms of Acute Hemolytic Transfusion Reactions Fever Chills Rigors Anxiety, feeling of doom Facial flushing Chest and abdominal pain Flank and back pain

Nausea and vomiting Dyspnea Hypotension Hemoglobinuria Oliguria/anuria Pain at the infusion site Diffuse bleeding

Differential Diagnosis Because patients receiving transfusion therapy can develop a clinical picture of hemolysis from many sources, it is important to distinguish an AHTR from acute hemolysis of other causes. Probably the most common cause of hemolysis in transfused patients is the improper storage of RBCs, leading to hemolysis of the unit; these events can occur if the blood is affected by thermal injury, subjected to mechanical trauma from constricted access lines or pressurized infusions, inappropriately mixed with hypotonic solutions or drugs, or contaminated by bacteria. These forms of nonimmune hemolysis can be avoided by careful attention to routinely available transfusion protocols for the storage and administration of blood components. Some patients with congenital or acquired forms of hemolytic anemia may be incorrectly assumed to have had an AHTR. Acute hemolysis in congenital hemolytic anemias such as hereditary spherocytosis, sickle cell anemia, or RBC enzyme deficiency states can occasionally be misidentified as an AHTR. Other conditions in critically ill patients can confuse transfusing clinicians, such as a coexistent microangiopathic hemolytic anemia, a patient with thrombotic thrombocytopenic purpura (TTP)/hemolytic-uremic syndrome (HUS), or patients with mechanical fragmentation of RBCs due to heart valves or other implanted circulatory devices.

49 669

Confirmation of the Diagnosis The initial suspicion of an AHTR should prompt discontinuation of the ongoing transfusion and an initial laboratory investigation (Table 49–2) including observation of the post-transfusion plasma for hemolysis and the performance of a direct antiglobulin test. Visual inspection of the plasma is subject to many causes of false-positive results, including the enumerated sources of nonimmune hemolysis, the presence of another hemolytic state, or an improperly drawn blood sample. The direct antiglobulin test also is subject to false-positive results. If either of these screening tests is positive, however, particularly in the presence of a compelling clinical story, further testing should be initiated in the transfusion service. Administration sets and blood bags should be examined, and the pretransfusion testing of the patient should be repeated. It is critically important in these cases to affirm the identity of the patient, to assure that the pretransfusion specimen was actually from the patient who encountered the reaction, to affirm that other patients are not involved in an identification error, and to withhold further transfusions unless urgently required until the presence or absence of an AHTR has been confirmed.

9/22/06 8:46:26 AM

TRANSFUSION MEDICINE

Table 49–2 Laboratory Investigations for Acute Hemolytic Transfusion Reactions Blood product Blood bank laboratory

Clinical laboratory

Confirm ABO, Rh Confirm other antigen types, if indicated Direct antiglobulin test Confirm ABO, Rh, antibody screen and identification Post-transfusion hemolysis check Complete blood count Platelet count Urinalysis for hemoglobin Serum bilirubin Creatinine, urine quantitation Coagulation profile DIC evaluation

DIC, disseminated intravascular coagulation.

The treating physician may want to order additional laboratory tests to confirm the clinical suspicion of an AHTR or to provide additional tests to facilitate therapy and monitor the patient’s status. These tests might include a complete blood count including platelets, coagulation screening, serum chemistries including creatinine, and tests to confirm hemolysis, such as haptoglobin, lactic dehydrogenase, and bilirubin. In complicated cases, a visual inspection of the post-transfusion blood smear also can be helpful. The laboratory may also be required to perform a more definitive evaluation for DIC in confirmed cases. III

Therapy

670

The first element of therapy of an AHTR is to stop the infusion of the suspected incompatible blood.16 It also is critical to maintain intravenous access for the patient, so the intravenous line should not be removed or sent to the laboratory for evaluation. In a suspected reaction, emergency measures may precede definitive confirmation. The early management should include careful monitoring of the vital signs, maintenance of the blood pressure and blood volume, and transfer of the patient to the appropriate acute care setting (most likely an intensive care unit [ICU]) for aggressive management, if required (Table 49–3). An intensive care specialist or a nephrologist or both should be consulted because dialysis therapy may be required. If AHTR due to ABO compatibility is confirmed, a pulmonary artery catheter may be critical for monitoring. Aggressive fluid replacement is subsequently administered, and vasopressors, such as dopamine, are commonly used in an attempt to mitigate renal complications.

Table 49–3

Diuretics such as furosemide are commonly administered to maintain urine output along with fluid support.17 If renal failure ensues, however, dialysis should be initiated promptly. In the event that bleeding ensues or the laboratory confirms that DIC has developed, supportive therapy with platelet concentrates and plasma products may become important. The use of heparin has been advocated to prevent or reduce the complications of DIC but may be difficult in the face of surgical bleeding.18 The use of protein C concentrates to interrupt DIC should also be considered, although clinical trial support is obviously lacking.19 The classic clinical descriptions of AHTR did not include the respiratory failure that can occur and is now more commonly recognized. Pulmonary function should be carefully monitored, with oxygen therapy and ventilator support initiated early by the intensive care specialists. Whether specific inflammatory inhibitors that have been studied for other chronic inflammatory states (inhibitors of IL-1 or TNF) would be useful is not known, but their use in severe situations appears justifiable.

PREVENTION The basic procedures used by blood banks for pretransfusion testing and management of transfusion practices are designed to eliminate AHTR. The most important cornerstone is the proper identification of the blood recipient and the collection of a carefully identified blood sample from the recipient for pretransfusion testing. Blood banking procedures are often deemed to be unnecessarily rigid by clinicians, but they must be enforced to lessen AHTR and other preventable transfusion consequences. The most effective systems require identification of the patient at the bedside and creating a unique identifier based on the personal identification by the phlebotomist. Barrier systems also prevent transfusion without the precise identification of the recipient.20 Computer technology is being adapted to make sample and recipient matching more rigorous in the hope of preventing transfusion errors and transfusion reactions.21 Another trend that should reduce transfusion reactions such as AHTR is the development of quality assurance systems (hemovigilance) that monitor transfusion practices, investigate transfusion reactions, reinforce training of physicians and nurses about transfusion care, and help to develop improved systems in hospitals to lessen transfusion risks. Once a sample is obtained in the blood bank, blood bank procedures are designed to detect ABO discrepancies and alloantibodies that can cause immune hemolysis and AHTR. Procedures are designed to be very sensitive so that antibodies will not be missed, but some highly sensitive procedures produce a problem with a high incidence of false-positive

Therapy for Acute Hemolytic Transfusion Reactions

General Considerations

Prevent Renal Complications

Pulmonary Complications

Management of DIC

Establish venous access

Maintain blood pressure and urine output Diuretics Dopamine Dialysis

Monitor pulmonary function Oxygen therapy Ventilator support

Consider heparin

Monitor vital signs ICU transfer Pulmonary artery catheter

Platelet transfusions Plasma for coagulopathy Protein C

DIC, disseminated intravascular coagulation; ICU, intensive care unit.

Ch49-F039816.indd 670

9/22/06 8:46:27 AM

that initiates the investigation of DHTR, prompted by the serologic findings observed in post-transfusion testing.30

Definition and Incidence Mollison24 defined DHTR as accelerated destruction of transfused red cells that begins only when sufficient antibody has been produced as a result of an immune response induced by the transfusion. Since the first case of DHTR attributed to Boorman and colleagues31 was reported in 1946, numerous cases have been described in the literature.32–37 Although exceptions are found,38–42 most DHTRs share these characteristics: 1. DHTRs generally occur in patients who have been alloimmunized to RBC antigens by previous transfusions or pregnancies. 2. Because the titer has decreased below detectable levels, the implicated antibody is not detected in pretransfusion antibody screening or compatibility testing. 3. DHTR is usually suspected 3 to 10 days after transfusion, when clinical symptoms associated with hemolysis are observed and/or serologic findings consistent with DHTR are noted (Table 49–4). 4. The clinical symptoms most frequently associated with DHTR include unexplained decreases in hemoglobin and hematocrit, fever, and jaundice. 5. The hallmark serologic findings in DHTR are the development of a positive direct antiglobulin test (DAT) and/ or a positive antibody screening test in post-transfusion testing because of the presence of RBC antibodies that were not detected in pretransfusion testing. 6. Antibodies directed against Rh (CEce) and Kidd (Jka, Jkb) system antigens are the antibodies most commonly implicated in DHTR; however, numerous other specificities have been described.

DELAYED HEMOLYTIC TRANSFUSION REACTIONS In contrast to AHTR, in which clinical symptoms occur immediately or within 24 hours of transfusion, delayed hemolytic transfusion reactions (DHTRs) are generally not recognized until 3 to 10 days after transfusion of blood that appeared to be serologically compatible.24–26 DHTRs commonly occur in patients who have been immunized to foreign blood group antigens during previous transfusions and/or pregnancies, but the antibody decreases over time and is not detected in subsequent pretransfusion testing. An anamnestic response is stimulated by the transfusion of seemingly compatible blood, causing increased production of antibody that sensitizes the antigen-positive donor RBCs leading to intravascular and/or extravascular hemolysis. Although the clinical symptoms associated with DHTRs are generally milder than those observed in AHTRs, DHTRs with severe hemolysis leading to disseminated intravascular hemolysis and acute renal failure have been reported.27–30 Because a time delay occurs between transfusion and the appearance of clinical sequelae in these cases, clinicians may not suspect DHTR.30 Often it is the blood bank or transfusion service

Table 49–4

The frequencies of DHTR reported in early studies vary widely.29,36 In the first series conducted at the Mayo Clinic from 1964 to 1973, the incidence of DHTR was reported as 1 DHTR per 11,650 RBC units transfused, with 22 (96%) of the 23 cases having clinical manifestations of hemolysis, and 3 deaths attributed to DHTR.29 In the second series from 1974 to 1977, the incidence of DHTR had increased to 1 DHTR per 4000 RBC units transfused, and only 24 (65%) of 37 had clinical evidence of hemolysis; the remaining 13 (35%) demonstrated serologic findings consistent with a DHTR, but no clinical or laboratory evidence of hemolysis was associated with transfusion.36 This

Event

Explanation

0 1 3–10 10–21

Pretransfusion tests negative Red cell transfusion Clinical signs of hemolysis may appear Post-transfusion sample: Positive DAT and positive antibody screen due to newly detected antibody DAT may become negative

Antibody titer below detectable levels

>21 to 300 days

49 671

Time Line of DHTR

Time (days)

>21

HEMOLYTIC TRANSFUSION REACTIONS

results due to clinically insignificant antibodies or other contaminating substances. In the case of AHTR, in which the culprit is most commonly a sampling problem en route to the laboratory, increased sensitivity in testing is unlikely to offer any real progress. Another common teaching by transfusion professionals is to avoid unnecessary transfusions, in part to reduce the fear that they may cause adverse consequences such as AHTR. Most hospitals have reduced their transfusion trigger for RBCs22 largely to handle concerns about infectious complications, so transfusion avoidance is not likely to reduce the rate of AHTR significantly. Because safe blood transfusion continues to depend on welltrained practitioners to obtain samples and administer blood products, it seems unlikely that enhanced training programs will ever totally eliminate this significant problem that is largely caused by human error. Technologic developments that might better handle this problem should be encouraged. The evolving capability to create universal group O blood by enzymatically removing A and B blood group antigens from RBC might be a technologic solution to the serious problem of AHTR.23

DAT may persist as positive; eluates may demonstrate alloantibody specificity or panagglutination

Accelerated destruction of transfused donor RBC Antibody titer increases; sensitizes donor red cells In vivo removal of antibody-sensitized donor red cells from the circulation Alloantibody binding nonspecifically to autologous RBC, or development of warm autoantibodies

DAT, direct antiglobulin test; DHTR, Delayed hemolytic transfusion reaction; RBC, red blood cell.

Ch49-F039816.indd 671

9/22/06 8:46:27 AM

TRANSFUSION MEDICINE

III 672

trend of increased frequency, but decreased clinical significance, appears to be related, in part, to the manner in which DHTRs were defined. If the frequency of DHTR is determined on the basis of clinical reporting alone, then the incidence would be far lower than the true rate, because the signs and symptoms of hemolysis are nonspecific and may be difficult to distinguish from the complicated medical course of multitransfused patients.26,27 If DHTR is defined by post-transfusion serologic testing, then the frequency is likely to increase, and the clinical findings may diminish, because correlation between serologic results and clinical hemolysis is often poor.30 The definition of DHTR was clarified by Ness and colleagues30 in 1990, when the authors introduced the term delayed serologic transfusion reaction (DSTR) to describe cases with serologic evidence of DHTR (i.e., the development of a positive post-transfusion DAT result and a newly identified alloantibody in eluate studies or plasma studies or both), but no clinical evidence of hemolysis. The authors strictly defined DHTR as a subset of DSTR in which clinical evidence of hemolysis was attributable to a transfusion reaction. In their series at the Johns Hopkins Hospital, only 6 (18%) of 34 consecutive patients identified with serologic findings consistent with DHTR had clinical evidence of hemolysis associated with transfusion and could be defined as DHTR by strict definition. Twenty-eight (82%) of the 34 DSTR cases had no clinical evidence of hemolysis, as determined by retrospective chart review. The ratio of DHTR to DSTR can be expressed as 18:82 (Table 49–5). The combined frequency of DSTR and DHTR was calculated as 1:1605 (0.06%) RBC units transfused. The frequency of true DHTR was only 1 case per 9094 units (0.01%) transfused. By using the same definitions as prescribed by Ness and colleagues,30 the Mayo Clinic reported a combined frequency of DHTR/DSTR as 1 per 1899 allogeneic RBC units transfused with a DHTR/DSTR ratio of 36:64 when patients were evaluated for clinical hemolysis concurrent with the detection of positive post-transfusion serology.43 The most recent study from the Mayo Clinic spanning the years 1993 to 1998 indicates a decline in DHTR and a concomitant increase in DSTR, which the authors attributed to the implementation of a moresensitive antibody screening method and a decrease in the average length of hospital stay for inpatients.44 Interestingly, their current rates of observed reactions and the DHTR/DSTR ratio are very similar to those reported by Ness and colleagues30 in 1990 (see Table 49–5).

Diagnosis The blood bank plays an important role in recognizing and reporting potential cases of DHTR. The clinician may submit a post-transfusion sample with a request for RBC transfusions, not suspecting that the patient’s decreased hemoglobin

and hematocrit are due to DHTR. Generally, positive antibody screening tests on the post-transfusion sample trigger antibodyidentification studies and investigation of DHTR. The laboratory investigation of DHTR is outlined in Table 49–6. The serologic findings in classic cases of DHTR include the development of a post-transfusion positive DAT that may have a mixed-field appearance because of the presence of IgG antibody–sensitized donor RBCs interspersed with DAT-negative autologous RBCs and the presence of a newly identified alloantibody in the red cell eluate or plasma studies or both approximately 3 to 10 days (or usually by 20 days) after the index transfusion (see Table 49–4).26 If the patient’s transfusion history and post-transfusion serologic findings are consistent with DHTR, then the patient should be evaluated for clinical and laboratory evidence of hemolysis associated with RBC transfusions (see Table 49–6). The patient’s physician should be notified, and a transfusion reaction report should be generated so that the findings become a part of the patient’s medical records.

Serologic Complexities of DHTR Diagnostic Difficulties For many years, it was generally accepted that in DHTR, the sensitized donor red cells would be removed from the circulation within approximately 14 days (or no later than 21 days) after the putatively responsible transfusion (see Table 49–4).26 Therefore, DAT and eluate studies should become negative coinciding with the in vivo destruction of transfused donor RBCs that provoked the immune response. It is now clear from long-term studies of DHTR that it is not uncommon for DAT to persist as positive because of IgG antibody or complement sensitization or both of RBCs for many weeks or months after the transfusion reaction, long after the transfused, antigen-positive donor RBCs would be expected to be removed from the circulation.30,45 In addition, these long-term studies showed that eluates prepared from samples drawn more than 6 months after DHTR, when all the transfused donor RBCs would have been removed from circulation, may still demonstrate the alloantibody responsible for the reaction. Several theories are proposed to explain these remarkable phenomena.26,45 Salama and Mueller-Eckhardt45 suggested that alloantibody binds nonspecifically in vivo to antigen-negative autologous red cells and activates complement via the classic pathway in all DHTRs. Thus DAT may remain positive long after the removal of transfused donor RBCs because of nonspecific sensitization of autologous RBCs with alloantibody or complement or both during DHTR.45–48 Although the mechanisms remain unclear and a subject of contention, the persistence of a positive DAT and reactive eluates after DHTR does not generally appear to correlate with in vivo hemolysis.26,30 The practical application of these long-term

Table 49–5 Incidence of Delayed Hemolytic Transfusion Reaction and Delayed Serologic Transfusion Reaction Series

Incidence*

DHTR/DSTR

Ness et al30 Johns Hopkins Hospital (Jan 1986–Aug 1987) Vamvakas et al43 Mayo Clinic (1980–1992) Pineda et al44 Mayo Clinic (1993–1998)

1:1605 1:1899 1:1300

18:82 36:64 19:81

*

Incidence expressed as DHTR/DSTR per number of red cell units transfused.

Ch49-F039816.indd 672

9/22/06 8:46:28 AM

HEMOLYTIC TRANSFUSION REACTIONS

Table 49–6

Outline for Laboratory Investigation of Suspected DHTR

1. Initial Serologic Investigation Post-transfusion sample tests Antibody identification studies: Initiated as a result of positive antibody screening tests (and/or positive DAT results) on the posttransfusion sample DAT profile: (DAT with polyspecific and monospecific anti-IgG and anti-C3 antiglobulin reagents) Eluate studies: Performed if DAT positive due to IgG sensitization of RBC and history of recent RBC transfusions 2. Supplemental Serologic Tests Retrieve pretransfusion sample (if available): Perform DAT and repeat antibody screening tests Retrieve retained segments from transfused RBC donor units: Phenotype for antigen corresponding to identified antibody 3. Review Serologic Findings and Transfusion History Results evaluated by transfusion medicine attending physician 4. Generate Suspected Transfusion Reaction Report The transfusion medicine attending physician assesses the patient for clinical signs and symptoms of DHTR and notifies the patient’s physician

studies of DHTR is the recognition that serology consistent with DHTR may persist long after the reaction has occurred and the patient has recovered. Consequently, serologic findings alone can be misleading and difficult to interpret. The investigation of DHTR must consider not only the serologic findings, but also the temporal relation of antigen-positive RBC transfusions to the serologic test results, coupled with a clinical evaluation and laboratory assessment of the patient for evidence of hemolysis associated with RBC transfusions. DHTR and Autoantibody Many anecdotal cases of allo- and autoimmunization occurring concurrently have appeared in the literature over the past 40 years.49–59 For example, Lalezari and colleagues55 described a patient who had DHTR due to allo-anti-D and subsequently developed autoantibodies. The post-transfusion DAT remained positive for 6 months after DHTR, and eluates demonstrated panagglutination consistent with the presence of warm autoantibodies having a broad specificity. Worlledge54 noted as early as 1978 that alloimmunization can lead to autoimmunization and that even immunized recipients who are given compatible blood may subsequently develop a positive DAT because of autoantibodies. It is not surprising that long-term studies by Ness and associates30 found that the development of warm autoantibodies after DHTR was relatively common. Approximately one third of patients with DHTR who were followed for more than 25 days after DHTR had persistence of a positive DAT due to warm autoantibodies with broad specificity (i.e., eluate panagglutinin) (see Table 49–4). The frequency of autoantibody development after DHTR may be even higher, because autoantibodies can mimic alloantibody specificities.58,59 It is possible that DHTR cases with apparent alloantibody recovered in long-term eluate studies may actually represent cases of warm autoantibodies mimicking alloantibody specificities.30,45 Although the postreaction autoantibodies appeared to be clinically benign in the cases followed by Ness and colleagues,30 some reports indicate that DHTRs have evolved into the production of pathologic warm autoantibodies leading to severe autoimmune hemolytic anemia.49–53

Severe DHTR Fortunately, the clinical symptoms in most DHTRs generally resolve within 2 to 3 weeks of the index transfusion without medical intervention other than transfusion support with

Ch49-F039816.indd 673

appropriate antigen-negative blood transfusions. However, severe DHTR with life-threatening anemia has been reported and occurs most often in alloimmunized patients with sickle cell disease (SCD).60,61 Because patients with SCD have a high alloimmunization rate ranging from 17.6% to 36%, they are at greater risk for DHTR.62–67 Frequencies of DHTR in SCD range from 4% to 22%63,66,69,70 compared with the frequency of true, clinical DHTR in all transfused patients of only 0.04% (one DHTR per 2537 transfused patients)71 to 0.1% (one DHTR per 854 transfused patients).30 The diagnosis of DHTR in patients with SCD may be difficult. Patients may have symptoms that are misdiagnosed as sickle cell pain crisis, and delays in initiating appropriate treatment could lead to significant morbidity or even death.72–77 Confusion can be avoided by making certain that an accurate transfusion history is obtained on admission and that a sample is sent to the transfusion service for processing in the event that blood transfusions are required. The causes of severe DHTR in SCD are unclear and controversial. Explanations for the profound anemia observed in severe DHTR include bystander hemolysis, sickle cell hemolytic transfusion reaction syndrome, and hyperhemolysis.60,61,78,79 Bystander hemolysis has been defined as the immune destruction of autologous RBCs that may occur during DHTR. The mechanism(s) of bystander hemolysis is unclear. One theory has proposed that activation of complement could occur when alloantibodies react with transfused antigen-positive donor RBCs, leading to destruction of allogeneic and “innocent bystander” autologous red cells.80–82 Bystander hemolysis is difficult to document but may be suspected when post-transfusion reaction hemoglobin and hematocrit are less than the pretransfusion values, suggesting that simultaneous destruction of transfused donor RBCs and autologous RBCs may be present. The phenomenon of bystander hemolysis in DHTRs has been reported in patients without SCD.80–82 However, bystander hemolysis may actually be more prevalent in patients with SCD, because sickle cells have a regulatory defect in the formation of the complement membrane attack complex, causing the cells to be more susceptible to complement-mediated hemolysis.83 Garratty71 suggested that complement activation in these cases may be triggered not only by antibody reacting with transfused RBC antigens, but also by antibody reacting with other foreign antigens (e.g., human leukocyte antigen [HLA], plasma proteins). Thus the mechanism of bystander hemolysis during DHTRs in patients with

49 673

9/22/06 8:46:28 AM

TRANSFUSION MEDICINE

SCD may be similar to that of paroxysmal nocturnal hemoglobinuria (PNH), in which immune complex formation may result in hemolysis of “innocent” autologous RBCs.82 One well-documented case of bystander hemolysis was reported by King and coworkers60 in a study in which they monitored five patients who had DHTR after preoperative exchange transfusions. By monitoring the hemoglobin A (transfused allogeneic donor RBCs) and hemoglobin S (autologous sickle cells) levels, the authors showed that in one of the cases, a substantial loss of autologous RBCs occurred (i.e., bystander hemolysis), as well as loss of allogeneic RBCs during DHTR. Petz and colleagues61 reported five cases of hemolytic transfusion reactions in SCD in which the severe anemia appeared to be due to the destruction of transfused donor RBCs coincident with suppression of erythropoiesis. The authors defined these cases as “the sickle cell hemolytic transfusion reaction syndrome,” in which reticulocytopenia coupled with the hemolysis of transfused donor RBCs caused life-threatening anemia. In their series, none of the patients appeared to have accelerated autologous RBC destruction (i.e., bystander hemolysis). Hyperhemolysis is a term that has been used to describe severe DHTR in SCD in which the ongoing hemolysis of autologous cells seems to be accelerated during the course of a hemolytic reaction.78,79 Win and associates78 suggested that the accelerated destruction of autologous cells that may occur in DHTR could be due to hyperactive macrophages that readily sequester both mature RBCs and reticulocytes. Interestingly, Darabi and Dzik84 recently reported hyperhemolysis after DHTR due to anti-K1 in a patient without SCD.

III

Treatment of Severe DHTR

674

Regardless of the mechanisms that may be involved, it is important to recognize that severe DHTR in patients with SCD is not an infrequent finding and may mimic a painful crisis.72–77 Effective treatment requires prompt diagnosis and conservative transfusion support with appropriate antigennegative RBCs. Steroid therapy and intravenous immune globulin infusions have been successfully used for the treatment of the most severe cases.78,79 Some have suggested administration of recombinant erythropoietin, depending on the patient’s reticulocyte count.85

Prevention of DHTRs The frequency of DHTRs has diminished with implementation of improved pretransfusion antibody-screening methods.44 The current challenge is to find a rapid, automated antibody-screening method that is sufficiently sensitive to detect most clinically important antibodies, but not so highly sensitive that clinically benign, unwanted antibodies are detected.86 Because antibody titers may decline below detectable levels, it is important that clinically significant antibodies be well documented in the transfusion service and medical records, and it may be helpful to provide patients with personal identification cards listing the antibodies and transfusion requirements.87,88 It must be emphasized that patients diagnosed with DSTRs are at risk for severe DHTR with future transfusions and must receive donor blood negative for the antigen(s) corresponding to the implicated alloantibodies.26,30

Ch49-F039816.indd 674

The high rate of alloimmunization and the high risk of DHTRs in SCD appears to be due, at least in part, to the disparity in antigen frequencies between the African American recipient and white donor population.63 For example, 73% of African Americans are C negative and may develop anti-C antibodies when transfused with blood from white donors, because 70% of whites are C positive. Therefore, increasing African American donations, particularly if the donations could be linked to patients with SCD requiring transfusion support, might be of benefit. It is generally accepted that patients with SCD should be extensively phenotyped (e.g., Rh antigens [CEce], K1, MNSs, Fya, Fyb, Jka, Jkb) so that antibodies the patients may potentially produce can be easily discerned.89–91 Having the extensive or complete phenotype on file is particularly advantageous in resolving complex antibody problems that are frequently presented by multitransfused patients with SCD. DNA typing for RBC antigens is now available and can be used in cases in which phenotyping is precluded by recent RBC transfusions or by scarcity of rare antisera.92,93 Prophylactic antigen matching of donor RBCs with the recipient’s complete phenotype has been advocated for patients with SCD in an effort to reduce the rate of alloimmunization and severe DHTR.89,90,94 Various transfusion protocols that differ in the number of antigens that are considered for prophylactic matching have been examined by Castro and colleagues94 Ness91 has proposed that prophylactic antigen matching should be considered only when the patient has developed one or more RBC alloantibodies, thereby indicating that the patient is a “responder” and may be at greater risk for further alloimmunization and DHTRs with subsequent RBC transfusions. This protocol is particularly appealing because it avoids unnecessary prophylactic antigen matching of donor blood for the approximately 70% of patients with SCD who do not become alloimmunized even after multiple transfusions. Prophylactic antigen matching may prevent some cases of DHTR, but even protocols that call for extensive prophylactic antigen matching cannot prevent severe hemolytic transfusion reactions due to unusual alloantibody specificities or the development of pathologic warm autoantibodies.60,95–97

FUTURE DIRECTIONS The development of blood substitutes for transfusion and/or exchange transfusion in SCD seems to offer the most hope for preventing severe DHTR and for circumventing difficulties in providing compatible blood for patients with complex antibody problems.98,99 With the rapidly growing sophistication of DNA technology, we may be able to distinguish “responders” from “nonresponders” by genotyping, so that special transfusion protocols could be applied more appropriately. Automated technology for rapid genotyping of blood donors is already under study and may permit the provision of genotypematched donor blood to recipients in the near future.100 REFERENCES 1. Davenport RD. Hemolytic transfusion reactions. In Popovsky MA (ed). Transfusion Reactions, 2nd ed. Bethesda, Md, American Association of Blood Banks, 2001, p 1. 2. Josephson CD, Mullis NC, Van Demark C, et al. Significant numbers of apheresis-derived group O platelet units have “high-titer” anti-A/A,B: Implications for transfusion policy. Transfusion 2004;44:805–808.

9/22/06 8:46:29 AM

Ch49-F039816.indd 675

32. Rauner RA, Tanaka KR. Hemolytic transfusion reactions associated with the Kidd system antibody (Jka). N Engl J Med 1967;276:1486. 33. Kurtides ES, Salkin MS, Widen AL. Hemolytic reaction due to anti-Jkb. JAMA 1966;197:816. 34. Fudenberg H, Allen FJ Jr. Transfusion reactions in the absence of demonstrable incompatibility. N Engl J Med 1957;256:1180–1184. 35. Walker PC, Jennings ER, Monroe C. Hemolytic transfusion reactions after the administration of apparently compatible blood. Am J Clin Pathol 1965;44:193–197. 36. Moore SB, Taswell HF, Pineda AA, et al. Delayed hemolytic transfusion reactions: Evidence of the need for an improved pretransfusion compatibility test. Am J Clin Pathol 1980;74:94–97. 37. Taswell HF, Pineda AA, Moore SB: Hemolytic transfusion reactions: Frequency and clinical and laboratory aspects. In Bell CA (ed). A Seminar on Immune-mediated Red Cell Destruction. Washington, D.C., American Association of Blood Banks, 1981, pp 71–92. 38. Taddie SJ, Barrasso C, Ness PM. A delayed transfusion reaction caused by anti-K6. Transfusion 1982;22:68–69. 39. Patten E, Reddi CR, Riglin H, et al. Delayed hemolytic transfusion reaction caused by a primary immune response. Transfusion 1982;22: 248–250. 40. Davey RJ, Gustafson M, Holland PV. Accelerated immune red cell destruction in the absence of serologically detectable alloantibodies. Transfusion 1983;23:40–44. 41. Baldwin ML, Barrasso C, Ness PM, et al. A clinically significant erythrocyte antibody detectable only by 51R survival studies. Transfusion 1983;23:40–44. 42. Kim HH, Park TS, Oh SH, et al. Delayed hemolytic transfusion reactions due to anti-Fyb caused by a primary immune response: a case study and review of the literature. Immunohematology 2004;20: 384–386. 43. Vamvakas EC, Pineda AA, Lreisner R, et al. The differentiation of delayed hemolytic and delayed serologic transfusion reactions: incidence and predictors of hemolysis. Transfusion 1995;35:16–32. 44. Pineda AA, Vamvakas EC, Gorden LD, et al. Trends in the incidence of delayed hemolytic and delayed serologic transfusion reactions. Transfusion 1999;10:1097–1103. 45. Salama A, Mueller-Eckhardt C. Delayed hemolytic transfusion reactions: evidence for complement activation involving allogeneic and autologous red cells. Transfusion 1984;24:188–193. 46. Chaplin H Jr. The implication of red cell-bound complement and delayed hemolytic transfusion reactions [Editorial]. Transfusion 1984; 24:185–187. 47. Salama H, Mueller-Eckhardt C. Binding of fluid phase C3b to nonsensitized bystander human red cells: A model for in vivo effects of complement activation on blood cells. Transfusion 1985;25:528–534. 48. Devine DV. Complement. In Anderson KC, Ness PM (eds). Scientific Basis of Transfusion Medicine: Implications for Clinical Practice, 2nd ed. Philadelphia, WB Saunders, 2000, pp 107–119. 49. Sosler SD, Perkins JT, Saporito C, et al. Severe autoimmune hemolytic anemia induced by transfusion in two alloimmunized patients with sickle cell disease [Abstract]. Transfusion 1989;29(Suppl):495. 50. Chaplin H Jr, Zarkowsky HS. Combined sickle cell disease and autoimmune hemolytic anemia [Abstract]. Arch Intern Med 1981;141:1091. 51. Reed W, Walker P, Haddix T, et al. Acute anemic events in sickle cell disease. Transfusion 2000;40:267–273. 52. Castellino SM, Combs MR, Zimmerman MA, et al. Erythrocyte autoantibodies in pediatric patients with sickle cell disease receiving transfusion therapy: frequency, characteristics and significance. Br J Haematol 1999;104:189–194. 53. Chan D, Poole GD, Binney M, et al. Severe intravascular hemolysis due to autoantibodies stimulated by blood transfusion. Immunohematology 1996;12:80–83. 54. Worlledge SM. The interpretation of a positive direct antiglobulin test. Br J Haematol 1978;39:157–162. 55. Lalezari P, Talleyrand NP, Wenz B, et al. Development of direct antiglobulin reaction accompanying alloimmunization in a patient with Rh(d) (D, category III) phenotype. Vox Sang 1975;28:19–24. 56. Cook IA. Primary rhesus immunization of male volunteers. Br J Haematol 1971;20:369–375. 57. Beard MEJ, Pemberton J, Blagdon J, et al. Rh immunization following incompatible blood transfusion and a possible long-term complication of anti-D immunoglobulin therapy. J Med Genet 1971;8:317–320. 58. Issitt PD, Zellner DC, Rolih SD, et al. Autoantibodies mimicking alloantibodies. Transfusion 1977;17:531–538. 59. Issitt PD, Pavone BG. Critical re-examination of the specificity of autoanti-Rh antibodies in patients with a positive direct antiglobulin test. Br J Haematol 1978;38:63–74.

HEMOLYTIC TRANSFUSION REACTIONS

3. Pineda AA, Brzica SM Jr, Taswell HF. Hemolytic transfusion reactions: recent experience in a large blood bank. Mayo Clin Proc 1978;53:378. 4. Lichtiger B, Perry-Thorton E. Hemolytic transfusion reactions in oncology patients: experience in a large cancer center. J Clin Oncol 1984;25:438. 5. Honig CL, Bove JR. Transfusion associated fatalities: review of Bureau of Biologics reports 1976–1978. Transfusion 1980;20:653. 6. Sazama K. Reports of 355 transfusion-associated deaths, 1976 through 1985. Transfusion 1990;30:583. 7. Robillard P, Itaj NK, Corriveau P. ABO incompatible transfusions, acute and delayed hemolytic transfusion reactions in the Quebec hemovigilance system-year 2000. Transfusion 2002;42:(Suppl): 25S. 8. Bluemle LW Jr. Hemolytic transfusion reactions causing acute renal failure: serologic and clinical considerations. Postgrad Med 1965; 38:484. 9. Davenport RD, Strieter RM, Kunkel SL. Red cell ABO incompatibility and production of tumour necrosis factor-alpha. Br J Haematol 1991;79:525. 10. Morat HZ, DiLorenzo NL. Activation of plasma kinin system by antigen-antibody aggregates. I: Generation of permeability factor in guinea pig serum. Lab Invest 1968;19:187. 11. Davenport RD, Strieter RM, Standiford TJ, et al. Interleukin-8 production in red blood cell incompatibility. Blood 1990;76:2439. 12. Davenport RD, Burdick MD, Streiter RM, et al. Monocyte chemoattractant protein production in red cell incompatibility. Transfusion 1994;34:16. 13. Pfueller SL, Luscher EF. Studies of the mechanisms of human platelet release reaction induced by immunologic stimuli. I: Complement-dependent and complement-independent reactions. J Immunol 1974;112:1201. 14. Davenport RD, Polak TJ, Schmouder RE, et al. Endothelial cell procoagulant activity inducted by red cell incompatibility. Transfusion 1994;34:943. 15. Goldfinger D. Acute hemolytic transfusion reactions: a fresh look at pathogenesis and considerations regarding therapy. Transfusion 1974;27:171. 16. Capon SM, Goldfinger D. Acute hemolytic transfusion reaction, a paradigm of the systemic inflammatory response: new insights into pathophysiology and treatment. Transfusion 1995;35:513. 17. Capon SM, Sacher RA. Hemolytic transfusion reactions: a review of mechanisms, sequelae, and management. J Intensive Care Med 1989;4:100–111. 18. Rock RC, Bove JR, Nemerson Y. Heparin treatment of intravascular coagulation accompanying hemolytic transfusion reactions. Transfusion 1969;9:57. 19. Rivard GE, David M, Farrell C, et al. Treatment of purpura fulminans in meningococcemia with protein C concentrate. J Pediatr 1995; 126:646. 20. Mercuriali F, Inghilleri F, Colotti MT, et al. One year use of the Bloodloc system in an orthopedic institute. Transfus Clin Biol 1994;1:227. 21. Dzik W. Emily Cooley Lecture 2002: Transfusion safety in the hospital. Transfusion 1003;43:11290. 22. Carson JL, Hill S, Carless P, et al. Transfusion triggers: a systematic review of the literature. Transfus Med Rev 2002;16:187. 23. Lenny LL, Hurst R, Goldstein J, et al. Transfusions to group O subjects of 2 units of red cells enzymatically converted from group B to group O. Transfusion 1999;34:209. 24. Mollison PL. Antibody-mediated destruction of red cells. Clin Immunol Newsl 1985;6:700–703. 25. Mollison PL. Blood Transfusion in Clinical Medicine, 9th ed. Oxford, Blackwell Scientific, 1993, pp 434–542. 26. Shirey RS, Ness PM. New concepts of delayed hemolytic transfusion reactions. In Nance SJ (ed). Clinical and Basic Science Aspects of Immunohematology. Arlington, Va., American Association of Blood Banks, 1991, pp 179–197. 27. Solanki D, McCurdy PR. Delayed hemolytic transfusion reactions: an often missed entity. JAMA 1978;239:729–731. 28. Holland PV, Wallerstein RO. Delayed hemolytic transfusion reaction with acute renal failure. JAMA 1968;204:1007–1008. 29. Pineda AA, Taswell HF, Brzica SM Jr. Delayed hemolytic transfusion reaction: An immunologic hazard of blood transfusion. Transfusion 1978;18:1–7. 30. Ness PM, Shirey RS, Thoman SK, et al. The differentiation of delayed serologic and delayed hemolytic transfusion reactions: incidence, long-term serologic findings and clinical significance. Transfusion 1990;30:688–693. 31. Boorman KE, Dodd BE, Loutit JF, et al. Some results of transfusion of blood to recipients with “cold” agglutinins. Br Med J 1946;i:751.

49 675

9/22/06 8:46:29 AM

TRANSFUSION MEDICINE

III 676

60. King KE, Shirey RS, Lankiewicz MW, et al. Delayed hemolytic transfusion reactions in sickle cell disease. Transfusion 1997;37:376–381. 61. Petz LD, Calhoun L, Shulman IA, et al. The sickle cell hemolytic transfusion reaction syndrome. Transfusion 1997;37:382–392. 62. Shirey RS, King KE. Alloimmunization to blood group antigens. In Anderson KC, Ness PM (eds). Scientific Basis of Transfusion Medicine: Implications for Clinical Practice, 2nd ed. Philadelphia, WB Saunders, 2000, pp 393–400. 63. Vichinsky EP, Earles PNP, Johnson RA, et al. Alloimmunization in sickle cell anemia and transfusion of racially unmatched blood. N Engl J Med 1990;322:1617–1621. 64. Rosse WF, Gallagher D, Kinney TR, et al. Cooperative study of sickle cell disease: transfusion and alloimmunization in sickle cell disease. Blood 1990;76:1431–1437. 65. Orlina AR, Unger PJ, Koshy M. Post-transfusion alloimmunization in patients with sickle cell disease. Am J Hematol 1978;5:101–106. 66. Cox JV, Steane E, Cunningham G, et al. Risk of alloimmunization and delayed hemolytic transfusion reactions in patients with sickle cell disease. Arch Intern Med 1988;148:2485–2489. 67. Ambruso DR, Githens JH, Alcorn R, et al. Experience with donors matched for minor blood group antigens in patients with sickle cell anemia who are receiving chronic transfusion therapy. Transfusion 1987;27:94–98. 68. Rosse WF, Telen M, Ware RE. Transfusion Support for Patients with Sickle Cell Disease. Bethesda, Md., AABB Press, 1998, pp 73–92. 69. Koshy M, Burd L, Wallace D, et al. Prophylactic red cell transfusions in pregnant patients with sickle cell disease: a randomized cooperative study. N Engl J Med 1988;319:1447–1452. 70. Diamond WJ, Brown Fl Jr, Bitterman P, et al. Delayed hemolytic transfusion reaction presenting as sickle-cell crisis. Ann Intern Med 1980;93:231–234. 71. Garratty G. Severe reactions associated with transfusion of patients with sickle cell disease [Editorial]. Transfusion 1997;37:357–361. 72. Heddle NM, Sortar RL, O’Hoski P, et al. A prospective study to determine the frequency and clinical significance of alloimmunization post-transfusion. Br J Haematol 1995;91:1000–1005. 73. Rao KR, Patel AR. Delayed hemolytic transfusion reactions in sickle cell anemia. South Med J 1989;9:1034–1036. 74. Kalyanaraman M, Heidemann SM, Sarnaik AP, et al. Anti-s antibodyassociated delayed hemolytic transfusion reaction in patients with sickle cell anemia. J Pediatr Hematol Oncol 1999;21:10–13. 75. Fabron JA, Moreira JG, Bordin JO. Delayed hemolytic transfusion reaction presenting as a painful crisis in a patient with sickle cell anemia. Rev Paul Med 1999;117:385–389. 76. Milner PF, Squires JE, Larison PJ, et al. Posttransfusion crises in sickle cell anemia: role of delayed hemolytic reactions to transfusion. South Med J 1985;78:1462–1469. 77. Petz LD, Garratty G. Acquired Immune Hemolytic Anemia, 2nd ed. New York, Churchill Livingstone, 2004, pp 547–549. 78. Win N, Doughty H, Telfer P, et al. Hyperhemolytic transfusion reaction in sickle cell disease. Transfusion 2001;41:323–328. 79. Cullis JO, Win N, Dudley JM, et al. Post-transfusion hyperhaemolysis in a patient with sickle cell disease: use of steroids and intravenous immunoglobulin to prevent further red cell destruction. Vox Sang 1995;69:355–357. 80. Polesky HF, Bove JR. A fatal hemolytic transfusion reaction with acute autohemolysis. Transfusion 1964;4:285–292. 81. Wiener AS. Hemolytic reactions following transfusions of blood of the homologous group. II: Further observations on the role of property

Ch49-F039816.indd 676

82. 83. 84. 85. 86.

87.

88. 89. 90. 91. 92. 93. 94.

95. 96. 97. 98. 99. 100.

Rh, particularly in cases without demonstrable iso-antibodies. Arch Pathol 1941;32:227–250. Petz LD. The expanding boundaries of transfusion medicine. In Nance LST (ed). Clinical and Basic Science Aspects of Immunohematology. Arlington, American Association of Blood Banks, 1991, pp 73–113. Test ST, Woolworth VS. Defective regulation of complement by the sickle erythrocyte: evidence for a defect in control of membrane attack complex formation. Blood 1994;83:842–852. Darabi K, Dzik S. Hyperhemolysis syndrome in anemia of chronic disease. Transfusion 2005;45:1930–1933. Telen MJ, Coombs M. Management of massive delayed hemolytic transfusion reactions in patients with sickle cell disease [Abstract]. Transfusion 1999;36(Suppl):97S. Bunker ML, Thomas Cl, Geyer SJ. Optimizing pretransfusion antibody detection and identification: a parallel, blinded comparison of tube PEG, solid-phase, and automated methods. Transfusion 2001;41: 621–626. Taswell HF, Pineda AA, Moore SB. Hemolytic transfusion reactions: Frequency and clinical and laboratory aspects. In Bell CA (ed). A Seminar on Immune-mediated Red Cell Destruction. Washington, D.C., American Association of Blood Banks, 1981, pp 71–92. Schonewille H, Haak HL, van Zijl AM. RBC antibody persistence. Transfusion 2000;40:1127–1131. Tahhan HR, Holbrook CT, Braddy LR, et al. Antigen matched donor blood in the transfusion management of patients with sickle cell disease. Transfusion 1994;34:562–569. Vichinsky EP, Luban NLC, Wright E, et al. Prospective RBC phenotype matching in a stroke prevention trial in sickle cell anemia: a multicenter transfusion trial. Transfusion 2001;41:1086–1092. Ness PM. To match or not to match: The question for chronically transfused patients with sickle cell anemia [Editorial]. Transfusion 1994;34: 558–560. Storry JR, Westhoff CM, Charles-Pierre D, et al. DNA analysis for donor screening of Dombrock blood group antigens. Immunohematology 2003;19:33–36. Hult A, Hellberg A, Wester ES, et al. Blood group genotype analysis for the quality improvement of reagent test cells. Vox Sang 2005;88: 465–470. Castro O, Sandler SG, Houston-Yu P, et al. Predicting the effect of transfusing only phenotype-matched RBCs to patients with sickle cell disease: Theoretical and practical considerations. Transfusion 2002;42:684–690. Strupp A, Cash K, Uehlinger J. Difficulties in identifying antibodies in the Dombrock blood group system in multiply alloimmunized patients. Transfusion 1998;38:1022–1025. Campbell SA, Shirey RS, King KE, et al. An acute hemolytic transfusion reaction due to anti-IH in a patient with sickle cell disease. Transfusion 2000;40:828–831. Callahan DL, Kennedy MS, Ranalli MA, et al. Delayed hemolytic transfusion reaction caused by Jk(b) antibody detected by only solid phase technique [Abstract]. Transfusion 2000;40(Suppl):113S. Lanskron S, Moliterno AR, Norris EJ, et al. Polymerized human Hb use in acute chest syndrome: a case report. Transfusion 2002;42:1422–1427. Winslow RM. Red cell substitutes. In Anderson KC, Ness PM (eds). Scientific Basis of Transfusion Medicine: Implications for Clinical Practice, 2nd ed. Philadelphia, WB Saunders, 2000, pp 588–598. Beiboer SHW, Wieringa-Jelsma T, VanWijk M. Rapid genotyping of blood group antigens by multiplex polymerase chain reaction and DNA microarray hybridation. Transfusion 2005;45:667–679.

9/22/06 8:46:30 AM