Immunity, major depression, and panic disorder comorbidity

The relation between immunologic variables and symptom factors in patients with major depressive disorder

BACKGROUND

The associations between depression and immunity were investigated by measuring the scores of Hamilton Rating Scale for Depression (HRSD) and peripheral lymphocyte parameters in patients with major depressive disorder (MDD).

METHODS

Forty-nine patients with MDD were recruited and their clinical symptoms are evaluated with 17-item HRSD which was factorized using the confirmatory factor analysis (i.e., depression factor, insomnia factor, and anxiety factor). Basic immunologic variables such as CD4, CD8, and CD56-positive cell numbers were measured by flow cytometry. Natural killer cell activity (NKCA) was also assessed by ELISA method using K-562 cells as target cells. All patients were treated for 4 weeks with selective serotonin reuptake inhibitors. Immunologic and clinical variables were measured both at baseline and after medication.

RESULTS

CD8-positive cell number was increased (p < .05) and CD4/CD8 ratio was decreased (p < .01) after medication. NKCA showed a significant positive correlation with anxiety factor scores of HRSD (p < .05) at baseline. However, except NKCA, there was no correlation between other immunologic measures and symptom factors.

CONCLUSION

These results suggest that immunologic measure such as NKCA may be an important variable for symptom of MDD such as anxiety during acute depressive state.

Recurrence of Panic Attacks after Influenza Vaccination: Two Case Reports

Human influenza is a contagious respiratory illness caused by the influenza virus. The influenza vaccination is recommended annually, but several adverse effects related to allergic reactions have been reported. Panic attacks are also known to occur, but no case of a panic attack adverse effect has been reported in South Korea. We present two cases of panic disorder patients whose symptoms were aggravated by the influenza vaccination. We assumed that dysregulation of T-lymphocytes in panic disorder patients could have a role in activating various kinds of cytokines and chemokines, which then can lead to panic attack aggravation.

An Act of Balance Between Adaptive and Maladaptive Immunity in Depression: a Role for T Lymphocytes

Historically the monoaminergic neurotransmitter system, in particular the serotonergic system, was seen as being responsible for the pathophysiology of major depressive disorder (MDD). With the advent of psychoneuroimmunology an important role of the immune system in the interface between the central nervous systems (CNS) and peripheral organ systems has emerged. In addition to the well-characterised neurobiological activities of cytokines, T cell function in the context of depression has been neglected so far. In this review we will investigate the biological roles of T cells in depression. Originally it was thought that the adaptive immune arm including T lymphocytes was excluded from the CNS. It is now clear that peripheral naïve T cells not only carry out continuous surveillance within the brain but also maintain neural plasticity. Furthermore animal studies demonstrate that regulatory T lymphocytes can provide protection against maladaptive behavioural responses associated with depression. Psychogenic stress as a major inducer of depression can lead to transient trafficking of T lymphocytes into the brain stimulating the secretion of certain neurotrophic factors and cytokines. The separate and combined mechanism of CD4 and CD8 T cell activation is likely to determine the response pattern of CNS specific neurokines and neurotrophins. Under chronic stress-induced neuroinflammatory conditions associated with depression, T cell responses may become maladaptive and can be involved in neurodegeneration. Additionally, intracellular adhesion and MHC molecule expression as well as glucocorticoid receptor expression within the brain may play a role in determining T lymphocyte functionality in depression. Taken together, T lymphocyte mechanisms, which confer susceptibility or resilience to MDD, are not yet fully understood. Further insight into the cellular and molecular mechanisms which balance the adaptive and maladaptive roles of T lymphocytes may provide a better understanding of both the neuro- degenerative and -regenerative repair functions as present within the neuroimmune network during depression. Furthermore T cells may be important players in restoration of normal behaviour and immune cell homeostasis in depression.

Decreased IFN-γ and IL-12 levels in panic disorder

OBJECTIVE

The aim of this study is to assess the measures of proinflammatory cytokines in patients with panic disorder in comparison with the healthy subjects.

METHODS

Twenty three patients with panic disorder with or without agoraphobia and twenty three controls were recruited for the study. Plasma samples of all subjects were analyzed for TNF-α, IFN-γ, IL-1β, IL-2, IL-6, and IL-12 concentrations and NK-cell activity is measured in the peripheral blood samples of the subjects.

RESULTS

We found significant differences on the mean values of IL-12 (p=0.01) and IFN-γ (p=0.02) between the panic disorder and control groups. In a logistic regression analysis, IFN-γ values were significant statistical predictors of the presence of panic disorder (B=-0.07, SE=0.03, p=0.04).

CONCLUSION

The most important implication of our results is to suggest a relation between panic disorder and low levels of IFN-γ, compatible with the results of the animal studies showing that IFN-γ plays a role by acting to regulate the development of anxiety-like behaviors.

Effects of venlafaxine and fluoxetine on lymphocyte subsets in patients with major depressive disorder: a flow cytometric analysis

BACKGROUND

Studies have yielded conflicting results concerning flow cytometric lymphocyte analyses in patients with depression. Data about the effect of antidepressants on lymphocyte subsets are also contradictory. The aim of this study was to determine effects of venlafaxine versus fluoxetine on lymphocyte subsets in depressive patients.

METHODS

Sixty-nine patients diagnosed with major depressive disorder (MDD) according to DSM-IV and 36 healthy controls are included in the study. Sixty-nine patients were randomized to take fluoxetine (FLX) (n=33) or venlafaxine (VEN) (n=36). Serum lymphocyte subsets included CD3, CD4, CD8, CD16/56, CD19, CD45, Anti-HLA-DR which were measured by flow cytometric analyses at baseline and 6 weeks after the start of treatment. The severity of depression was evaluated with Hamilton rating scale for depression.

RESULTS

At baseline, patients with MDD had significantly lower CD16/56 ratio and higher CD45 ratio compared to the controls. Although numerically higher in the VEN treated patients, treatment response rates between the FLX (53%) and the VEN (75%) groups were not different statistically. CD45 values decreased significantly in the VEN group at the end of the 6 week treatment period whereas no difference was observed in the FLX group. By the 6th week, treatment responders showed a significantly higher CD16/56 ratio than non-responders. Baseline severity of depression and anxiety was positively correlated with baseline CD45 ratio and negatively correlated with baseline CD16/56 ratio. We did not observe consistent changes in the absolute number of circulating B or T cells, nor in the helper/inducer (CD4) or suppressor/cytotoxic (CD8) subsets.

CONCLUSIONS

CD16/56 was lower in patients with MDD and increased in treatment responders at 6th week. CD45 ratio was higher in patients with MDD than healthy subjects; it decreased with antidepressant treatment and was positively correlated with the severity of depression. Antidepressant treatment contributes to immune regulation in patients with major depressive disorder.

Effects of experimentally induced panic attacks on neuroimmunological markers

Since little is known concerning regulation of immunological parameters in rapid changing psychiatric states like panic attacks, we measured cytokines at different time points in healthy subjects, which underwent experimental panic induction using the CCK-4 paradigm. Apart from a challenge related IL-6 increase, we could not observe any changes of neuroimmunological markers in relation to acute anxiety with regard to time and group. Herein we conducted for the first time a new approach to immunological research in panic disorder, suggesting immune changes are more related to long term disease stress.

Nitric oxide, adenosine deaminase, xanthine oxidase and superoxide dismutase in patients with panic disorder: alterations by antidepressant treatment

OBJECTIVE

In the present study, we aimed to investigate whether nitric oxide (NO) levels and activities of xanthine oxidase (XO), superoxide dismutase (SOD), and adenosine deaminase (ADA) are associated with Panic disorder (PD) as well as impact of psychopharmacological treatments on NO, SOD, ADA, and XO levels in PD.

METHOD

In this study, 32 patients and 20 healthy controls were included. The serum levels of NO, XO, SOD, and ADA were measured in the patients and controls. The patients were treated with antidepressant.

RESULTS

ADA and XO levels of the patients were significantly higher than the controls. SOD levels of the patients were significantly lower than the controls but the difference was not statistically significant. Although NO levels of the patients were higher than the controls, the difference was not statistically significant. There was no correlation between PAS and the parameters studied (SOD, ADA, XO, and NO) of the patients. After 8 weeks of antidepressant treatment, ADA and SOD activities were increased whereas NO and XO levels decreased significantly.

CONCLUSION

ADA, XO activity may have a pathophysiological role in PD, and prognosis of PD. Activity of these enzymes may be used to monitor effects of the antidepressant treatment.

Immunological aetiology of major psychiatric disorders: evidence and therapeutic implications

Historically, immunological research in psychiatry was based on empirical findings and early epidemiological studies indicating a possible relationship between psychiatric symptoms and acute infectious diseases. However, aetiopathological explanations for psychiatric disorders are no longer closely related to acute infection. Nevertheless, immune hypotheses have been discussed in schizophrenia, affective disorders and infantile autism in the last decades. Although the variability between the results of the epidemiological studies conducted to date is strikingly high, there is still some evidence that the immune system might play a role in the aetiopathogenesis of these three psychiatric diseases, at least in subgroups of patients. In anxiety disorders immunological research is still very much in its infancy, and the few and inconsistent data of immune changes in these patients are believed to reflect the influence of short- or long-term stress exposure. Nevertheless, there are also some hints raising the possibility that autoimmune mechanisms could interrupt neurotransmission, which would be of significance in certain patients with anxiety and panic disorders. Drug and alcohol (ethanol) dependence are not believed to be primarily influenced by an immunological aetiology. On the other hand, immune reactions due to different drugs of abuse and alcohol may directly or indirectly influence the course of concomitant somatic diseases. In different organic brain disorders the underlying somatic disease is defined as a primary immune or autoimmune disorder, for instance HIV infection or systemic lupus erythematosus (SLE). For other neurodegenerative disorders, such as Alzheimer's disease, immunoaetiopathological mechanisms are supported by experimental and clinical studies. Treatment strategies based on immune mechanisms have been investigated in patients with schizophrenia and affective disorders. Furthermore, some antipsychotics and most antidepressants are known to have direct or indirect effects on the immune system. Different immunotherapies have been used in autism, including transfer factor, pentoxifylline, intravenous immunoglobulins and corticosteroids. Immunosuppressive and/or immunomodulating agents are well established methods for treating the neuropsychiatric sequelae of immune or autoimmune disorders, for example AIDS and SLE. Therapeutic approaches in Alzheimer's disease also apply immunological methods such as strategies of active/passive immunisation and NSAIDs. Considering the comprehensive interactive network between mind and body, future research should focus on approaches linking targets of the different involved systems.

Lymphocyte subsets and mood states in panic disorder patients

This study was conducted to examine lymphocyte subset counts and mood states in panic disorder patients. Twenty patients with panic disorder and 20 age- and gender-matched normal healthy subjects were recruited for the study. We used the Spielberger State (STAIS) & Trait (STAIT) Anxiety Inventory, Hamilton Depression Rating scale (HAMD) and Hamilton Anxiety Rating scale (HAMA) to measure mood states in all subjects. Lymphocyte subsets counts were made by flow cytometry. Panic patients showed significantly higher scores for anxiety and depression than normal subjects. Panic patients showed no differences in terms of the numbers of immune cells, as compared with normal healthy subjects, other than a lower proportion of T suppressor cells and a higher T helper cell/T suppressor cell ratio. HAMA and STAIS scores were common factors that could predict T cell numbers and proportions, T helper cell numbers, and natural killer cell proportions in panic disorder patients. We suggest that anxiety levels are related to the T-cell population in panic disorder patients and that quantitative immune differences may reflect altered immunity in this disorder.

Panic disorder and immunity: few effects on circulating lymphocytes, mitogen response, and NK cell activity

Altered immune measures are commonly found in major depression (MD), however, less is known about the immune system in anxiety disorders. We examined quantitative and functional in vitro immune measures in patients with panic disorder (PD), which is often comorbid with MD. Fourteen otherwise healthy medication-free adults (ages 23-49; 11 female) meeting SCID-UP DSM-IIIR criteria for PD with agoraphobia and without current MD, were compared with 14 subjects free of PD, MD, or other major psychiatric disorders, matched by gender, age, and racial background. PD was associated with decreased percentage (p<.03) and total (p<.03) circulating CD19+ B lymphocytes, but no differences in other enumerative lymphocyte measures. Mitogen responses (Con A, PHA, PWM) did not differ except for possibly decreased PHA in PD (p<.06). NK cell activity did not differ between PD and control subjects. The few immune measure changes in PD contrast with those found in MD, providing further evidence for the specificity of immune changes in psychiatric disorders.

Relationship between separation anxiety disorder, parental panic disorder, and atopic disorders in children: a controlled high-risk study

OBJECTIVE

To test the hypotheses that rates of atopic disorders are elevated in offspring of parents with panic disorder (PD) and in children with separation anxiety disorder (SAD).

METHOD

Rates of atopic disorders were assessed in 343 offspring (aged 6-17 years) of parents with PD, nonpanic psychiatric disorders, and no psychiatric disorder. Lifetime history of atopic disorders was determined by parental responses to a clinician-administered questionnaire assessing medical treatment for asthma and allergies. Logistic regression analyses assessed the association between atopic disorders and parental PD, and between atopic disorders and probable or definite childhood SAD. Analyses controlled for age, sex, socioeconomic status, and treatment for other medical illnesses.

RESULTS

Increased rates of atopic disorders were found in offspring of parents with PD (odds ratio [OR] = 2.56, 95% confidence interval [CI] = 1.27-5.16, p = .009) and in children with SAD (OR = 2.71, 95% Cl = 1.22-6.03, p = .015). Associations remained significant when both parental PD and SAD were included in the model, suggesting that each contributed independently to increased rates of atopy. The interaction of parental PD and child SAD was not significant.

CONCLUSIONS

Atopic disorders in children are associated with parental PD and with childhood SAD. Results do not appear to support that having both childhood SAD and a parent with PD confers increased risk for atopic disorders above and beyond either condition alone.

Plasma levels of tumor necrosis factor-alpha in patients with panic disorder: effect of alprazolam therapy

Plasma concentrations of tumor necrosis factor-alpha (TNF-alpha) were measured in 10 outpatients with panic disorder, twice (at a 48-h interval) before and twice on days 30-32 of treatment with alprazolam (2-2.5 mg/day), and twice in 10 age- and sex-matched healthy controls. TNF-alpha concentrations did not differ in patients and control subjects, either before therapy or at days 30-32 of therapy. In five patients before therapy, and in three of them after therapy, TNF-alpha values were higher than the maximal concentrations of the cytokine in controls.

Pathways linking major depression and immunity in ambulatory female patients

OBJECTIVES

The goals of this study were to investigate whether depression is associated with cellular immunity in ambulatory patients and to identify neuroendocrine and behavioral pathways that might account for this relationship.

METHODS

We studied 32 women who met Diagnostic and Statistical Manual of Mental Disorder, fourth edition, criteria for major depressive disorder and 32 healthy female control subjects. The groups were matched for age and ethnicity. None were taking medication, and all were free of disease involving the immune system.

RESULTS

Depressed subjects had reduced proliferative responses to the mitogens concanavalin A and phytohemagglutinin compared with control subjects. Natural killer cell activity was reduced among older depressed subjects but enhanced among younger depressed subjects. Although depression was associated with elevated circulating levels of norepinephrine and estradiol, these hormones could not account for the immunologic differences between depressed and control subjects. Depression was also associated with greater tobacco and caffeine consumption, less physical activity, and poorer sleep quality. Mediational analyses were consistent with physical activity acting as a pathway through which depression was associated with reduced lymphocyte proliferation.

CONCLUSIONS

Ambulatory patients with mild to moderately severe depression exhibit reduced mitogen-stimulated lymphocyte proliferative responses and altered natural killer cell cytotoxicity. The relationship between depression and proliferative responses may be mediated by physical activity.

Immune correlates of depression

The relation of depression to immunological assays is complex and variable. However, meta-analyses have demonstrated that depressed subjects are likely to show changes in several immune assays. Depressed subjects are likely to have changes in major immune cell classes with an increase in total white blood cell counts and a relative increase in numbers of neutrophils. However, the relative number of lymphocytes is likely to be reduced in depressed subjects. Depression also appears to be associated with increases in at least one measure of immune activation, although further investigations are clearly needed to replicate these interesting observations. Finally, depression is reliably associated with a suppression of mitogen-induced lymphocyte proliferation and with a reduction of NK activity. Despite the heterogeneity of findings, the effect sizes in the relationship between depression and lymphocyte proliferation and NK activity are large as compared to those observed in other areas of psychological and medical research. Several moderating factors may explain and account for the heterogeneity that has been found in the depression-immune results. Future immunologic studies in depressed subjects are needed to clarify the effects of gender and reproductive hormones on the relation between depression and immunity. Severity of melancholic symptoms and sleep disturbance appear to moderate the immune changes in depression but the biological mechanisms that account for the link between these neurovegetative symptoms and depression are not yet known. Finally, assessment of co-morbidity in depressed subjects deserves an increased focus. Data generated from our laboratory clearly show that assessment of alcohol- and tobacco dependence is critical in the interpretation of immune changes in depressed subjects. The clinical significance of changes in immune responses in depressed subjects remains an unanswered question. Studies that use immune measures with disease specific endpoints, as has been recently conducted in the study of VZV immune responses, would help identify the possible link between depression, immune system alterations, and health outcomes.

Effects of comorbidity on health-related quality-of-life scores: an analysis of clinical trial data

Coexisting diseases may have unforeseen yet clinically significant effects on patients' well-being. Both generic and disease-specific measures are frequently used to assess health-related quality of life (QOL). The present study assessed the effects of comorbidity on the results of QOL measures through an analysis of longitudinal data from 3 double-masked, randomized, placebo-controlled clinical trials dealing with heartburn, asthma, and ulcer. Patients were assigned to subgroups by comorbidity status: those with no comorbid diseases and those whose principal disease was heartburn, asthma, or ulcer and whose comorbid condition was chronic obstructive pulmonary disease, asthma, or chronic bronchitis; hypertension; migraine, coronary artery disease, or varicose veins; chronic gastrointestinal conditions; arthritis or back pain; diabetes; or depression. Multivariate analysis of covariance was used to test the study hypotheses. The study results suggest that comorbid conditions significantly and extensively affect patients' scores on generic QOL measures and estimation of treatment effect, whereas their influence on disease-specific QOL scores and estimation of treatment effect is considerably smaller. Further, the most important comorbidities in the 3 trial populations were arthritis or back pain and depression, which respectively accounted for 17% and 5% of the patient population. These findings have significant practical implications for the estimation of true treatment effects, control of comorbidity effects, and design of QOL trials.

Circulating lymphocyte phenotypic surface markers in anxiety disorder patients and normal volunteers

BACKGROUND

Although the relationship between stress and immune function is an area of active investigation, there have been few reports studying the relationship between anxiety disorders and the immune system.

METHODS

This study employs flow cytometry to measure circulating lymphocyte phenotypic markers in 20 medication-free patients with panic disorder, 33 medication-free patients with generalized social phobia, and 32 healthy controls.

RESULTS

Both patients with panic disorder and patients with social phobia had increased CD16 (natural killer) cell numbers. Panic disorder patients also had increased numbers of CD19 cells (B lymphocytes), human leukocyte antigen (HLA)-DR-presenting cells, and more cells with the combination of HLA-DR and CD19 surface markers (B lymphocytes with HLA-DR on their surface).

CONCLUSIONS

These preliminary data suggest that subjects with panic disorder may have alterations in circulating lymphocyte profiles.

Phagocytosis and killing of Staphylococcus aureus: effects of stress and depression in children

While a large body of literature depicting relationships between depression or stress and immunity exists, few such studies have dealt with children, and none investigated myeloid cell-derived immunity. We investigated both phagocytosis and bactericidal activity against Staphylococcus aureus in children with major depressive disorder (MDD). We found that both MDD and stress influence the bactericidal but not the phagocytic activity of polymorphonuclear leukocytes. The data support the existence of psychobiologic effects in children and suggest possible mechanisms by which depression and stress may affect health.

Stress versus depression

1. Exhaustive evidence is quoted showing that uncontrollable (uncoping) stress provoked in experimental mammals leads to depletion of central noradrenergic activity+ adrenomedullary-cortical gland hyperactivity. These physiological disorders cause the typical neuroendocrine peripheral profile: a) raised catecholamines (CA) in plasma [noradrenaline (NA)+adrenaline (Ad)+dopamine (DA), b) reduced NA/Ad ratio in plasma and c) raised plasma cortisol. 2. Exhaustive evidence is quoted which indicates that severely ill humans show peripheral neuroendocrine profile similar to that found in mammals submitted to uncontrollable stress situation. Further, the NA/Ad ratio does not increase but decreases during orthostasis and exercise stress challenges, as well as oral glucose stress (tolerance) test. 3. Exhaustive evidence is quoted which indicates that endogenous depressed subjects show a neuroendocrine profile opposite to that observed in stressed mammals and severely ill humans. This profile consists of central NA (neural sympathetic) hyperactivity+ adrenomedullary glands hyporresponsivity. These disorders are reflected in a three to ten fold increase of the NA/Ad ratio in plasma. 4. Exhaustive evidence is also quoted showing that dysthymic depressed patients show low plasma catecholamines+low NA/Ad plasma ratio (< 2) during supine-resting condition, it is normalized at orthostasis and exercise periods. 5. It is quoted evidence showing that whereas platelet serotonin is increased in dysthymics, the same is reduced in both endogenous depressed and stressed mammals as well as severely ill humans. 6. It is quoted evidence showing that free serotonin in plasma is greatly raised in uncoping stressed mammals and severely ill humans. The same parameter is normal or slightly increased in dysthymic and endogenous depressed humans. These findings are consistent with the increased platelet aggregability observed in "uncontrollable" stressed mammals and in severely ill, but not depressed patients. 7. It is also quoted evidence showing that whereas parasympathetic activity is absent in uncontrollable stressed mammals and severely ill humans, the same is increased in both types of depressed humans. 8. According to the above, the authors postulate the existence of 3 distinct central+ peripheral neuroendocrine profiles for endogenous depression, dysthymic depression and maladaptation to stress syndrome. These different profiles should lead researchers to attempt different therapeutical approach. 9. In view of the fact that the authors found much clinical overlap among the three syndromes (endogenous depression, dysthymic depression and severely ill patients), they believe that a differential diagnosis should be based on neurochemical, neuroendocrine, physiologic, metabolic and neuropharmacological grounds. 10. The experimentally induced uncontrollable stress (behavioral despair) syndrome in mammals should not be used as a valid model of human depressive syndrome.

Respiratory disorders as a possible predisposing factor for panic disorder

150 consecutive anxiety patients completed a specially designed questionnaire which asked for the occurrence of respiratory and other somatic disorders before the onset of their anxiety disorder. The sample was divided into 82 panic disorder patients and 68 other anxiety patients serving as controls. Panic disorder patients had a significantly higher prevalence of respiratory diseases before the onset of their anxiety disorder than controls (42.7 vs. 16.2%). This higher prevalence was mainly due to a higher prevalence of bronchitis (26.8 vs. 8.8%). Differences in numbers of respiratory disorders mentioned appeared not to result from a tendency to hypochondria.

Anxious symptoms influence delayed-type hypersensitivity skin test in subjects devoid of any psychiatric morbidity

The present study aimed to evaluate the relationship between anxious/depressive symptoms and cell-mediated immunity (Delayed-type Hypersensitivity skin test, DTH) in subjects devoid of any psychiatric morbidity. Forty-eight females and twenty-four males were studied, ages ranging 21-60. These subjects completed the Beck Depression Inventory (BDI) for evaluation of depressive symptoms and the State-Trait Anxiety Inventory (STAIX1, STAIX2) for evaluation of anxious symptoms; subsequently on the same day they were tested for DTH using the Multitest CMI system (Merieux Institute, France). Subjects were split into three groups using the 33rd and 66th percentiles of DTH response (cumulative induration diameter). In females, subjects with larger DTH response (DTH > 8 mm) had significantly lower levels of "state" anxiety (scores at STAIX1; Kruskall-Wallis test, P = .04). On the contrary, no differences were observed between groups considering scores obtained by males at self-evaluation rating scales. Our data seem to support the hypothesis that activity of immune system as measured by DTH skin test may be influenced by affective status in the context of everyday life.

[Psychoimmunology and AIDS: a review of the literature]

In recent years, several studies have been carried out concerning the effect of psychosocial factors on the course of infection due to the human immunodeficiency virus (HIV). After summarizing the current status of general knowledge in the field of psychoimmunology, this article reviews the results of studies conducted in regard to HIV. Two conclusions are reached. The first is that current research has not shown psychosocial factors to have any impact on either the immunity status of seropositive patients or the medical complications inherent to AIDS. The second conclusion is that several types of intervention, in particular psychoeducational approaches, stress management programs, and the strengthening of social and family support, give good results where the psychosocial well-being of patients is concerned and should motivate various health professionals to improve the focus of their interventions. Furthermore, significant methodological weaknesses in several indexed studies are noted, and these should be rectified to enable future studies to confirm or correct the present observations.

Serum cytokine and soluble interleukin-2 receptors in patients with panic disorder

There has been very little research investigating the interface between panic disorder and the immune system. This preliminary study explores the relationship between panic disorder and serum levels of cytokines, which have potent immune and central nervous system activity, and soluble interleukin-2 receptors, a well-known marker of T-cell activation. Fifteen women with panic disorder and 19 healthy female subjects had serum levels of interleukin-1, interleukin-2, and soluble interleukin-2 receptors (SIL-2Rs) measured by enzyme-linked immunoassay. Women with panic disorder had slightly increased serum levels of interleukin-2 but did not differ from age-comparable and gender-matched controls in serum interleukin-1 alpha, or interleukin-1 beta. And although the mean SIL-2R levels were not different for the two groups, the SIL-2R levels were present across a wider range of values in the women with panic disorder. Our data suggest that more extensive investigation of circulating levels of interleukin-2 and the soluble interleukin-2 receptor in patients with panic disorder may be warranted.

Serum interleukin-2 and soluble interleukin-2 receptor levels in generalized social phobia

Alternations in immune function have been described in a variety of psychiatric disorders including schizophrenia and depression; however, we do not know of any research involving social phobia and the immune system. This preliminary study explores the relationship between social phobia and two well-established immune parameters, serum interleukin-2 (IL-2) levels, a potent immune and central nervous system modulator, and soluble interleukin-2 receptors (SIL-2Rs), a well-known marker of T-cell activation. Fifteen subjects with generalized social phobia and 15 healthy volunteers had serum IL-2, and SIL-2Rs measured by enzyme-linked immunoassay. Subjects with social phobia and normal volunteers had similar mean serum IL-2 and SIL-2R levels. The data suggest that, unlike other psychiatric disorders, these immune measures may not be used to differentiate patients with generalized social phobia from normal volunteers.

Depression, adrenal steroids, and the immune system

During the past decade, over 30 studies have examined the immune system in depression. While a number of investigators have reported depression-related alterations in peripheral blood immune cell number and function, many researchers have been unable to replicate these findings. The relationship between depression and the immune system has turned out to be much more complex than was initially anticipated. Factors which have complicated the interpretation of the research include the heterogeneity of depressed patients, the variability of immune assays, and the clinical relevance of these assays. In this review we conclude that alterations in the immune system do not appear to be a specific or reproducible biological correlate of depression but may occur in association with other variables which characterize depressed patients including age, sex and severity of depression. Conceptual frameworks for future research on the immune system and depression are discussed and include: (i) depression as a cofactor in the development, course and outcome of diseases involving the immune system; (ii) depression as a neuroimmunological disease; and (iii) depression as a model for studying neuroendocrine-immune interactions in humans. In terms of this third line of research, patients with depression consistently have been shown to display abnormalities in the secretion of adrenal steroids, and new data is presented which indicates that adrenal steroids may play a much more complex role in the modulation of the immune response than has been previously appreciated.