Impaired lymphocyte function in depressive illness

Stress, immunity and illness--a review

Psychological factors have long been thought to play a contributing role in either the predisposition, onset or course of various physical illnesses. Recently, rapid advances in immunology have created interest in the interaction between psychosocial factors, behaviour and the immune system. This paper reviews some of the models proposed to explain the relationship between psychological variables and physical illness and presents evidence for a contribution of psychological factors to certain illnesses in which abnormalities in immunologic state are thought to be important. From a somewhat different perspective, animal studies have demonstrated complex effects of stress, on disease susceptibility. Recent human studies have demonstrated consistent immunologic changes in people undergoing acute naturally occurring psychological stress such as bereavement or an important examination. In humans, the effects of chronic stress may be different from acute stress, corresponding to the findings in animals. Abnormalities in immunologic functioning and physical illness are reviewed for different psychiatric disorders--depression, anorexia nervosa and schizophrenia; depression is the only disorder which consistently demonstrated immunologic changes. Possible mechanisms for the stress/immune-change relationship are suggested.

Lithium and immune function

Lithium has potent antiviral and immunostimulating properties which are probably consequences of its actions on prostaglandin synthesis. Although lithium has considerable potential in the prophylaxis of some viral illnesses and other manifestations of defective immune function, it is, paradoxically, capable of activating autoimmune mechanisms in predisposed patients.

Impaired natural killer cell activity during bereavement

Natural killer (NK) cell activity, a component of the immune surveillance system, was compared in women whose husbands had recently died with that found in age-matched women who had not experienced recent adverse life events. Bereaved women had significantly lower NK activity than women whose husbands were healthy. In a second study, depressive symptoms and NK activity were measured longitudinally in women before and after the death of their husbands. Our results suggest that depressive symptoms, not merely the death of the spouse, are related to a reduction in NK activity during bereavement.

Influence of desmethylimipramine on natural killer cell activity

Mounting evidence suggests that the central nervous system (CNS) and the immune system are extensively interconnected. One question that arises is whether there is cross-reactivity between psychotropic agents, which are active in the CNS, and immune system function. To explore this notion, we examined the in vitro effect of the tricyclic antidepressant, desmethylimipramine (DMI), on human natural killer (NK) cell activity in seven separate experiments. At concentrations greater than or equal to 625 ng/ml, DMI reliably inhibited NK activity. Preincubation of lymphocytes with DMI before assay did not increase the inhibitory effect. Furthermore, removal of the drug from preincubated cells immediately before assay completely eliminated the inhibitory effect. These results demonstrate that DMI reversibly inhibits NK activity at serum concentrations that are not uncommonly found in depressed patients receiving this medication.

Immunological response to stress in agoraphobia and panic attacks

The authors studied in vitro immune function as measured by lymphocytic proliferative response to mitogen stimulation in 36 patients with agoraphobia and panic attacks who were participating in a double-blind placebo-controlled psychopharmacological study of anxiety disorder. No significant difference in immune status was observed between panic patients and healthy controls.

Depression and carcinoma of the pancreas

A systematic psychiatric evaluation of 21 subjects with intraabdominal malignancy (pancreatic or gastric carcinoma) was performed. Depression was frequently associated with and often the presenting symptom complex of patients with carcinoma of the pancreas. This finding was not observed in patients with gastric carcinoma. Clinical and theoretical implications of these findings are discussed.

Depression, immunocompetence, and prostaglandins of the E series

Plasma prostaglandin E1 and E2, and quantitative and qualitative measures of immune function, were determined in depressed patients and healthy controls. Prostaglandin E2 was significantly elevated in the depressed group, and prostaglandin E1 showed a trend in the same direction. Lymphocyte stimulation responses, as measured by phytohemagglutinin, concanavalin A, and pokeweed mitogen, were significantly lower in the depressed group. Helper and suppressor T cell percentages did not significantly differ in the two populations. In the depressed group, prostaglandin E1 showed a significant inverse correlation with concanavalin A, and prostaglandin E2 showed a similar trend. These preliminary data suggest prostaglandins of the E series may be related to abnormalities of cellular immunity previously documented in depression.

Depression, urinary free cortisol excretion and lymphocyte function

An impairment in lymphocyte response to mitogen stimulation, a correlate of cell-mediated immunity, has been reported in patients with depressive illness. To investigate whether such impairment in lymphocyte function is related to excessive secretion of cortisol, an immunosuppressive hormone, we compared mitogen-induced lymphocyte proliferation in three groups of subjects: depressed patients with elevated 24-hour urinary free cortisol (UFC) excretion; depressed patients with normal UFC excretion; and normal controls. Depressed patients in both groups showed significant reductions in lymphocyte mitogenic activity, in comparison with the normal controls, but the two depressive groups did not significantly differ from each other in their lymphocytic responses to any of the mitogens used. Furthermore, no significant correlations were found, within depressed patients, between UFC excretion and lymphocyte mitogenic responses. Depression is therefore associated with an impairment in lymphocyte function that cannot be explained solely on the basis of increased cortisol secretion.

Depression, cortisol metabolism and lymphocytopenia

Depression is often associated with hypercortisolemia. Because high levels of cortisol influence the distribution of different types of leukocytes in the blood stream, we examined the percentages and absolute numbers of circulating neutrophils and lymphocytes in 29 depressed patients who were nonsuppressors on the Dexamethasone Suppression Test (DST), 28 depressed patients who were suppressors on the DST, and 52 schizophrenic controls. We found no significant differences in either RBC or WBC counts in the 3 groups. There were, however, significant differences in the percentages of both neutrophils and lymphocytes as well as the absolute number of lymphocytes among the groups. These differences were mostly due to significantly lower lymphocyte percentages and absolute counts in the depression-nonsuppressor group. We also found a significant negative association between post-dexamethasone plasma cortisol concentrations and blood lymphocyte counts. These data suggest a close interaction between cortisol metabolism and lymphocyte regulation in major depression.

A controlled study of cellular immune function in affective disorders before and during somatic therapy

Lymphocyte blastogenesis induced by lectins (PHA, Con A, and PWM) was assessed in 27 drug-free patients with unipolar (n = 21) or bipolar (n = 5) depression and 13 normal controls. Fifteen patients were restudied after clinical remission. Symptomatic patients did not differ from controls nor did endogenous and nonendogenous depressions differ in their lymphocyte blastogenesis response to any of the three lectins. However, a significant reduction in lymphocyte blastogenesis with both PHA and Con A stimulation was found following somatic treatment. Cellular immune function appears to be normal in depressed patients, although the somatic therapies are associated with a reduction in this function.

Stress, affective disorders, and immune function

Increasing scientific evidence supports age-old observations that psychosocial factors are closely associated with the pathogenesis of certain physical and mental illnesses. The immune system appears to play a primary mediating role. Whereas acute stress may initiate a transient immunologically protective response, prolonged or poorly controlled psychosocial stressors may result in depression of different components of the immune system. These responses may be related to, or independent of, changes in the neuroendocrine system. As the rather prolific literature in this infant area of psychoneuroimmunology reveals, there are many complex levels of interaction that require further investigation. There is clearly a need for long-term prospective studies that will identify individuals at risk for those numerous diseases in which psychosocial factors and impaired immune function play a pathogenic role. In addition to correlating altered immune function over time with changes in the physical environment, these studies should include psychologic profiles, life-event inventories, and psychiatric interviews in an effort to delineate the role of psychosocial factors as the stimulus for and as the response to the disease process. One of the many positive outcomes of this multifactorial approach to illness is that it will alter the physician's approach to disease and thus to patients as they are evaluated and treated in the psychosocial context in which they live. As Hippocrates said, "It is more important to know what sort of a person has a disease than to know what sort of disease a person has."

Antidepressant tachyphylaxis

We report eleven patients in whom tachyphylaxis to antidepressants, lithium or ECT occurred. These cases are a small sample of patients we have encountered in whom an initial good response to mood regulating drugs was not sustained. We suspect that systematic studies would reveal that tachyphylaxis is a common phenomenon with antidepressant therapies.

Leukocyte regulation in depression and schizophrenia

The distribution of leukocytes in the blood stream is affected by levels of circulatory glucocorticoids. Elevated concentrations of cortisol are usually associated with an increase in the number of neutrophils and a decrease in the number of lymphocytes. Since primary depressive illness is often associated with hypercortisolemia, we hypothesized that similar changes in the blood stream of depressive patients may occur. To test this hypothesis, we retrospectively compared leukocyte counts in 177 untreated depressive patients and 178 untreated schizophrenic controls. We found a significant increase in the absolute and relative numbers of neutrophils and a significant decrease in the absolute and relative numbers of lymphocytes in the depressive group. Furthermore, when compared to normative values from the general population, depressed patients showed higher frequencies of both neutrophilia and lymphopenia than the schizophrenic group. These results indicate differences in the regulation of leukocytes in depression and schizophrenia consistent with the effects of higher levels of plasma cortisol in the depressive group.