Lymphocyte proliferation among major depressive and dysthymic patients with typical or atypical features

Background: Depressive illness may be associated with immune and cytokine a lterations. However, data are unavailable concerning functional immune chan ges associated with chronic, low-grade depression (dysthymia). Moreover, th e contribution of the neurovegetative features of depression (e.g., altered sleep, eating) to the immune alterations remains to be determined. Methods : Mitogen-stimulated cell proliferation was assessed in major depressive an d dysthymic patients exhibiting either typical or atypical features. In a s ubset of patients, lymphocyte proliferation was also assessed before and af ter pharmacotherapy to determine whether alleviation of symptoms would be a ccompanied by normalization of immune functioning. Results: Lymphocyte prol iferation was reduced to a greater extent among dysthymic than among major depressive patients. Among dysthymic patients reduced cell proliferation wa s evident irrespective of symptom typicality; however, among major depressi ve patients the contribution of neurovegetative features varied with the sp ecific mitogen used. Symptom alleviation following antidepressant treatment was not accompanied by normalization of cell proliferation. Limitations: P atients received 12 weeks of antidepressant treatment, and more sustained t herapy may be required for normalization of immune activity. As well, concl usions concerning normalization of immune functioning in drug-treated major depressive patients requires that a greater number of patients be assessed . Conclusions: As the immune variations were more pronounced in dysthymia t han in major depression, chronicity of illness may be a pertinent factor in promoting immune disturbances. This does not exclude the possibility that depression is associated with immune activation, which then provokes suppre ssion of other aspects of immunity. As well, it is conceivable that immune alterations indirectly contribute to the symptoms accompanying depressive s tate, although it does not appear that variations of lymphocyte proliferati on are associated with neurovegetative status. (C) 2000 Elsevier Science B. V. All rights reserved.