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.