Endocrine and cytokine correlates of major depression and dysthymia with typical or atypical features

Depression has been associated with both suppression and enhancement of various aspects of immune functioning. It was of interest to determine whether cytokine alterations associated with depression, including interleukin-1 (IL-1 beta) and interleukin-2 (IL-2), were related to the neurovegetative symptom profile or to the chronicity of the illness. Circulating ACTH, cortisol, norepinephrine (NE) and epinephrine levels, and production of IL-1 beta and IL-2 from mitogen-stimulated lymphocytes were assessed in classical major depression, atypical depression (ie. with reversed neurovegetative features), and dysthymia (chronic depression without comorbid major depression) with either typical or atypical profiles, as well as nondepressed control subjects. Among atypical depressives, plasma ACTH levels were elevated while cortisol was reduced relative to controls. Irrespective of neurovegetative profile, IL-1 beta production was increased in dysthymic patients, and was highly correlated with age-of-onset and duration of illness. In contrast, IL-2 production was reduced in each of the groups, although less so among atypical major depressives. Moreover, IL-2 production in the depressive groups was directly related to plasma NE levels, While neither depressed mood per se nor neurovegetative features accounted for this effect, it seemed likely that chronicity of illness or age-of-onset were associated with cytokine alterations. Given that circulating cytokines influence neuroendocrine functioning, and may affect neurovegetative features, a role for interleukins may exist with respect to the pathophysiology of certain subtypes of depression.