Immunological alterations in adult obsessive-compulsive disorder

Immunological Alterations in Adult Obsessive-Compulsive Disorder Donatella Marazziti, Silvio Presta, Chiara Pfanner, Alfredo Gemignani, Alessandra Rossi, Silverio Sbrana, Valeria Rocchi, Fabio Ambrogi, and Giovanni B. Cassano Background: Some recent findings suggest the involvement of autoimmune mechanisms in childhood onset of obsessive-compulsive disorder (OCD), on the basis of a parallel drawn with Sydenham’s chorea, a manifestation of rheumatic fever. A monoclonal antibody called D8/D17 characterizing a B-lymphocyte antigen, present in almost all patients with rheumatic fever, has been found also in children affected by OCD, Tourette syndrome, and chronic tics to a greater degree than in healthy control subjects. The few observations of disturbances of some immunologic parameters in adult OCD patients, prompted the authors to investigate and compare subsets of peripheral immunological cells for differences in adult patients with OCD and healthy control subjects. Methods: Twenty patients suffering from OCD, with no comorbidity for other psychiatric disorders, were compared with a similar group of healthy control subjects. The immune subsets were measured by flow cytometry. Results: The CD8⫹ lymphocytes were significantly increased and CD4⫹ lymphocytes significantly decreased in OCD patients, while the other cells did not differ between the two groups. No correlation was found between immunologic and clinical parameters. Conclusions: These data indicate that patients with adult OCD showed increased CD8⫹, i.e., suppressor T lymphocytes, and decreased CD4⫹, which identify helper T lymphocytes, as compared with a similar group of healthy control subjects. The findings appear peculiar to patients with OCD and are suggestive of an immunologic imbalance, which might be related to the stress deriving from the frustrating situation determined by the disorder itself. Biol Psychiatry 1999;46:810 – 814 © 1999 Society of Biological Psychiatry

From the Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie (DM, SP, CP, AG, AR, GBC); and the Unit of Immunology, University of Pisa, Pisa, Italy (SS, VR, FA). Address reprint requests to Dr. Donatella Marazziti, Dipartimento di Psichiatria, Neurobiologia, Farmacologie e Biotecnologie, University of Pisa, via Roma, 67, 56100 Pisa, Italy. Received May 5, 1998; revised September 22, 1998; accepted November 18, 1998.

© 1999 Society of Biological Psychiatry

Key Words: Obsessive-compulsive disorder, immune system, peripheral immunological cells, CD8⫹ lymphocytes, CD4⫹ lymphocytes, CD4⫹/CD8⫹ ratio

Introduction

T

he specific response of obsessive-compulsive disorder (OCD) patients to drugs which increase the intrasynaptic availability of serotonin (5-HT), such as selective 5-HT reuptake inhibitors (SSRIs) (Zohar and Insel 1987; Leonard et al 1989; Montgomery 1994, 1996; Greist et al 1995; Piccinelli et al 1995; Fineberg 1996), has directed biologic research toward the exploration of the possible involvement of the 5-HT system in OCD (Insel et al 1985). Most of the findings, derived from different lines of research, support a possible role of 5-HT in OCD (Asberg et al 1981; Hollander et al 1988; Zohar et al 1988; Marazziti et al 1992a, 1996) but the meaning of the disturbance, be it in etiologic or pathophysiologic terms, as well as its precise location with regard to the 5-HT transporter or receptor subtype, are still to be determined (Marazziti et al 1994; Sasson and Zohar 1996). In addition, the hypothesis that OCD might be underlined by a unique neurochemical abnormality, contrasts with the observation that at least 30% of patients do not respond to SSRIs, and with the notion that there might be different mechanisms underlying the overall clinical heterogeneity of OCD patients (Montgomery 1994; Sasson and Zohar 1996). Some attempts have been made to subgroup OCD patients, even on the basis of differences in peripheral central nervous system markers, such as 3H-imipramine binding sites, coupled with the 5-HT transporter and peripheral benzodiazepine receptors, which are thought to be distributed differently in chronic and episodic OCD (Ravizza et al 1991), although controversies do exist on this issue. On the other hand, broader agreement exists regarding the possibility of some forms of childhood OCD being due to immunologic alterations, on the basis of the possible shared involvement of basal ganglia abnormali0006-3223/99/$20.00 PII S0006-3223(98)00371-0

Immunological Alterations in Adult OCD

ties in OCD and Sydenham’s chorea, both resulting from infection-driven autoimmune processes (Swedo 1994). Sydenham’s chorea is a manifestation of rheumatic fever, following an infection provoked by group A ␤-hemolytic streptococci, which is thought to derive from the production of antibodies cross-reacting with neurons of the basal ganglia (Bronze and Dale 1993). The relationship between OCD and Sydenham’s chorea is strengthened by clinical observations showing that more than 80% of children with this last condition show obsessions and compulsions both before, and concomitantly with, choreic movements (Swedo 1994), and that one third of OCD children present choreiform movements (Denckla and Rapoport 1989). As a result, the hypothesis has emerged that infections with group A ␤-hemolytic streptococci might produce conditions grouped together under the name of PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococci), including subtypes of pediatric OCD and tics (Swedo et al 1994, 1997, 1998), but the observation has been made that even viral infections might trigger the autoimmune process leading to OCD (Allen et al 1995; Khanna et al 1997). Furthermore, patients with rheumatic fever show a high level of antineural antibodies against the caudate (Husby et al 1976) and a particular antigen in B lymphocytes reacting with a monoclonal antibody called D8/D17 (Zabriskie 1986; Gibofsky et al 1991). Such an antigen has been shown to be stable in different populations and over time and, more interestingly, it is also present in patients with childhood OCD, Tourette syndrome, and chronic tic disorder (Murphy et al 1997); preliminary data are available also in subjects with autism (Hollander et al 1998). Although the relationship between the antigen identified by the D8/17 antibody and the pathophysiology of the various disorders is not yet clear, it has been considered either as an immunologic marker of susceptibility to rheumatic fever (Gibofsky et al 1991) or to be linked to the motor component of the various disturbances (Kiessling et al 1993). Various reports have indicated the presence of immune system alterations in adult OCD patients (Maes et al 1994; Weizman et al 1996; Brambilla et al 1997; Khanna et al 1997). We, therefore, decided to investigate lymphocyte subsets in a population of adult OCD patients, as compared with healthy control subjects.

Methods and Materials Subjects Twenty patients (15 women and 5 men; between 17 and 54 years of age, mean ⫾ SD 26.7 ⫾ 8.9) were selected from the outpatient unit of the Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Section of Psychiatry at Pisa University from among those with OCD, according to DSM-IV criteria

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(American Psychiatric Association 1994), who were neither depressed, as assessed by the total score at the Hamilton rating scale for depression (HAM-D; Hamilton 1960) that ranged from 0 to 3, nor suffered from current comorbid psychiatric conditions. Diagnoses were made by resident physicians with at least 4 years of clinical experience under the supervision of senior psychiatrists. The severity of symptoms was assessed by means of the Yale Brown Obsessive-Compulsive Scale (Y-BOCS; Goodman et al 1986). The Y-BOCS total score was 25 ⫾ 4.3 (minimum 19, maximum 33), the O subscale total score was 13.7 ⫾ 2.3, and the C subscale total score was 11.3 ⫾ 2.8. The age at onset (mean ⫾ SD) was 19.8 ⫾ 2.5 and the length of illness (years, mean ⫾ SD) was 6.9 ⫾ 7.8. The most commonly reported obsessions were aggressive (78.9%), and the most common compulsions were cleaning (63.2%) and checking (57.9%). Seventeen patients were at the first psychiatric interview and were unmedicated; 3 had a history of treatment (clomipramine, imipramine, and benzodiazepines) halted 6 months previously. The patients were compared with 20 healthy subjects who served as controls (15 women and 5 men; between 28 and 55 years of age, mean ⫾ SD 27.4 ⫾ 6.3), without any familial or past or current personal history of major psychiatric disorders. Neither patients nor healthy subjects had any recent or current evidence of somatic diseases, were heavy cigarette smokers, suffered from any primary disease interfering with immune functions, or belonged to AIDS risk groups, and they all had blood and urine test results within the normal range. After providing all subjects with a complete description of the study, which had been approved by the Ethics Committee at Pisa University, informed written consent to participate in it was obtained. Ten ml of venous blood was drawn from one-night fasting subjects between 7:00 and 8:00 AM and in the spring, in order to exclude circadian or seasonal rhythms, and was transferred to plastic tubes with heparin as anticoagulant. Blood was drawn from a patient and a control subject at the same time and the analyses were performed within 1 hour of collection by the immunologists, who were blind to the condition of the samples. Cytofluorimetric analysis was carried out on a two-color Facstar Flow Sorter apparatus (Becton-Dickinson, USA), equipped with Consort 30 software, using a dual-angle light scatter lymphocyte gate. The following fluorescein (FITC) or phycoerythrin (PE)conjugated monoclonal antibodies (MoAbs), were used: CD4⫹ (Leu-3a; Coulter-Clone), CD8⫹ (Leu-2a; Coulter-Clone), CD3⫹ (Leu-4: Coulter-Clone), CD19⫹ (Leu-12; Coulter-Clone), and CD56⫹ (Leu-19: Becton-Dickinson). Quality control was performed according to the criteria prescribed by the first European Quality Control of Cellular Phenotyping by Flow Cytometry (Martini et al 1990). The balance between T-helper and T-suppressor lymphocytes was evaluated by means of the ratio CD4⫹/CD8⫹. Statistical comparisons were made by t test (unpaired, twotailed). The correlation between Y-BOCS total and subscale scores or age, age at onset, and duration of illness, on the one hand, and lymphocyte parameters, on the other, was assessed according to Pearson’s method by means of microcomputer programmes (Statview V, McIntosh, 1992) (Nie et al 1975).

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Table 1. Lymphocyte Subsets (Mean ⫾ SD) and CD4⫹/CD8⫹ (T Helper/T Suppressor) Ratio in OCD Patients and Control Subjects Patients % ⫹

CD3 CD19⫹ CD8⫹ CD4⫹ CD16/56⫹ CD4⫹/CD8⫹ ratio

Control subjects an

72 ⫾ 5 1190 ⫾ 104 11 ⫾ 3 142 ⫾ 23 33 ⫾ 6a 789 ⫾ 186b 43 ⫾ 8c 828 ⫾ 54d 12 ⫾ 5 110 ⫾ 20 1.40 ⫾ .4e

%

an

75 ⫾ 4 1207 ⫾ 87 10 ⫾ 2 150 ⫾ 15 27 ⫾ 4 403 ⫾ 114 49 ⫾ 1 923 ⫾ 78 12 ⫾ 3 112 ⫾ 18 1.89 ⫾ .59

an, absolute number. a significant: p ⫽ .002. b significant: p ⫽ .001. c significant: p ⫽ .003. d significant: p ⫽ .003. e significant: p ⫽ .004.

Results The results showed that OCD patients had increased CD8⫹ T cells, as compared with healthy control subjects, both in terms of percent values (mean ⫾ SD, 33 ⫾ 6 vs. 27 ⫾ 4; p ⫽ .002) and absolute number (mean ⫾ SD, 789 ⫾ 186 vs. 403 ⫾ 114; p ⫽ .001), and decreased CD4⫹ T cells (mean ⫾ SD, percent values, 43 ⫾ 8 vs. 49 ⫾ 1; p ⫽ .003; absolute number, 828 ⫾ 54 vs. 923 ⫾ 78; p ⬍ .003), while the CD3⫹, CD19⫹, and CD56⫹ lymphocyte subpopulations were unchanged. The ratio CD4⫹/CD8⫹ was 1.40 ⫾ .4 in patients and 1.89 ⫾ .59 in healthy control subjects, statistically lower in the first group than in the second (p ⫽ .004) (Table 1). No significant correlation between the severity of OC symptoms or clinical parameters and immunological cells was observed.

Discussion The results of our study indicated a significant increase in CD8⫹ (T-suppressor) and decrease in CD4⫹ (T-helper) lymphocytes in both percentage and absolute number in a group of adult OCD patients, as compared with healthy control subjects. The alterations in these two subsets of T lymphocytes did not appear to be linked to any somatic diseases, which were excluded, or to any clinical feature or symptom severity, since no correlation between them and clinical parameters was observed. However, the findings of increased CD8⫹ and decreased CD4⫹ cells seem to be peculiar to OCD, since they are at variance with what is reported in depression. In this condition, although controversies do exist, different signs of immune activation have been reported, in particular, leukocytosis, an increased number of CD4⫹, CD7⫹/CD25⫹, HLA-DR⫹ cells, and an

increased CD4⫹/CD8⫹ ratio, while the number of CD8⫹ lymphocytes appears to have decreased (Irwin et al 1990; Muller et al 1993; Maes et al 1996). With regard to anxiety disorders, in the past, our group has reported a decreased number of CD4⫹ cells in panic disorder patients (Marazziti et al 1992b). The observation of the same abnormality in OCD patients would suggest that T-helper lymphocytes might be linked to, or influenced by, psychic anxiety. Such findings are usually interpreted as indices of disturbances at the level of the interaction between the immune system and the hypothalamic–pituitary–adrenal (HPA) axis, but it is still a matter of debate whether they might be considered primary or secondary phenomena (Irwin et al 1990; Maes 1995). Interestingly, decreased CD4⫹ cells have been oberved also in patients with autism (Warren et al 1986), a disorder characterized also by obsessive-compulsive symptoms which has been linked recently to OCD via a dimensional approach (Hollander et al 1998). Alterations in immunologic mechanisms have been implicated in the pathophysiology of some subtypes of OCD, such as a childhood form following streptococcal infections, which might be due to autoimmune mechanisms (Swedo 1994). This notion is supported by the finding of antibodies against basal ganglia in some OCD patients (Husby et al 1976; Bronze and Dale 1993). In addition, recently, a B-lymphocyte antigen called D8/D17, which is present in almost all patients with rheumatic fever, has been reported in more than 20% of OCD patients (Zabriskie 1986). Such an antigen has been generally interpreted as indicating vulnerability towards the development of Sydenham’s chorea after rheumatic fever (Gibofsky et al 1991; Feldman et al 1993) and, according to Murphy et al (1997), it characterizes also a childhood onset OCD that might be considered as a kind of less severe Sydenham’s chorea. It is worth noting that such an antigen has been observed also in other related disorders such as Tourette’s syndrome, tic disorder, and autism (Murphy et al 1997; Hollander et al 1998). The literature regarding immunologic factors in adult OCD is quite meager. Cytokine production appears to be normal in OCD patients, at variance with depressives (Weizman et al 1996). Barber et al (1996) evaluated T-lymphocyte subsets in chronic OCD patients in the acute phase, but were unable to find any difference in comparison with healthy control subjects, either before or after successful clomipramine treatment. However, the sample size was very small (7 cases), the patients were suffering from mild to moderate OCD, and had received medication in the past, although treatment had been halted 1 month before the assay. On the other hand, the possible involvement of the immune system in some subtypes of OCD is supported by the finding of a relationship between the severity of the disorder and the interleukin-6 (IL-6)

Immunological Alterations in Adult OCD

and IL-6 receptor levels (Maes et al 1994) and by the observation of decreased plasma cytokines, such as interleukin-1 beta and tumor necrosis factor alfa (Brambilla et al 1997), which has been related to hyperactivity of the noradrenergic system and of the HPA axis. However, childhood OCD appears to differ from that occurring at other ages, in that increased cerebrospinal fluid (CSF) levels of cell-mediated cytokines have been reported (Mittleman et al 1997) in children with OCD, as compared with children with schizophrenia or attention deficit hyperactivity disorder. The role of immune factors in OCD is also supported by the report of increased CSF levels of immunoglobulin G antibodies against herpes virus of type 1, suggestive of a chronic infection, in an Indian sample of adult patients (Khanna et al 1997) but the specificity of these findings needs to be clarified. It is difficult to provide an explanation for our results, but certainly they would seem to underline the need for a more thorough investigation of the immune mechanism in OCD and in psychiatric disorders in general. One initial consideration that can be put forward is that there different OCD subtypes do exist and some patients may present distinct immunologic abnormalities producing specific immunologic patterns which could be of help in characterizing them. Immunologic alterations appear to be different in children and adult patients and probably reflect different pathophysiologic mechanisms, such as autoimmune and possibly, primary processes in the first case, and perhaps, secondary alterations in adulthood. Furthermore, it would be helpful to identify familial, clinical, or symptomatologic features that might be linked to a CD4⫹ decrease and/or CD8⫹ lymphocyte increase. This last disturbance has been reported in association specifically, with psychologically frustrating situations, which offer no possibility of control and result in hopelessness and helplessness (Knapp et al 1992; HoffmanGoetz and Pedersen 1994). It may be that the obsessive ideation and compulsive behavior represent the substrate of frustration provoked by the efforts made to cope with and to resist them (Brosschot et al 1992). Similarly, it would seem feasible that patients with other OCD-related disorders might perhaps share the same immunologic pattern. Whether or not this is so, the presence of immunologic disturbances might suggest the use of nonconventional treatments, in particular antibiotics or immunomodulators (Swedo et al 1994; Allen et al 1995) not only in children, but also in adult OCD patients.

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