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.