RELATIONSHIPS BETWEEN INTERLEUKIN-6 ACTIVITY, ACUTE-PHASE PROTEINS, AND FUNCTION OF THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS IN SEVERE DEPRESSION

Recent studies from this laboratory have provided some evidence that m ajor depression, in particular melancholia, may be accompanied by an i mmune response. The present study was designed to investigate whether severe depression is characterized by increased interleukin-6 (Il-6) a ctivity and whether Il-6 production is related to altered levels of ac ute phase reactants and to abnormal function of the hypothalamic-pitui tary-adrenal (HPA) axis. Measurements were made in 8 healthy control s ubjects and 24 depressed inpatients of Il-6 production in culture supe rnatants of mitogen-stimulated peripheral leukocytes and plasma levels of haptoglobin (Hp), transferrin (Tf), and postdexamethasone cortisol . Il-6 activity was significantly higher in melancholic subjects than in healthy control subjects and in patients with minor depression or n onmelancholic major depression. Il-6 production was significantly corr elated with Hp (positively) and Tf (negatively) plasma levels. There w ere significant and positive correlations between Il-6 activity and po stdexamethasone cortisol values. The findings may suggest that increas ed Il-6 activity in severe depression is related to hypotransferrinemi a, hyperhaptoglobinemia, and hyperactivity of the HPA axis.