MULTIPLE RECIPROCAL RELATIONSHIPS BETWEEN IN-VIVO CELLULAR-IMMUNITY AND HYPOTHALAMIC-PITUITARY-ADRENAL AXIS IN DEPRESSION

Major depression is reportedly characterized by increased activity of the hypothalamic-pituitary-adrenal (HPA) axis and by in vivo immune activation. The present study was carried out in order to investigate the relationships between HPA-axis activity and in vivo immune function in depression. Towards this end the following parameters were measured: 24 h urinary cortisol (UC) excretion; basal and post-dexamethasone (DST) plasma cortisol, beta-endorphin/beta-lipotropin (betaEND/betaLPH) and dexamethasone concentrations; and leucocyte subsets (i.e. lymphocytes, neutrophils, monocytes, CD4+, CD4+CD45RA+, CD4+CD45RO+, CD8+, CD8+CD57+, CD8-CD57-, HLA-DR+, CD25+T cells, HLA-DR+, CD19+, CD20+, and CD21+ B cells) both pre- and post-DST. Dexamethasone administration (I mg orally) induced leucocytosis, lymphocytopaenia, monocytopaenia and neutrophilia. HPA-axis non-suppressors exhibited a relative resistance to the enhancing (e.g. neutrophils) or depressant (e.g. lymphocytes, CD4+ T cells) effects of dexamethasone. There were significant correlations between UC excretion and the number of percentage of lymphocytes, monocytes, CD4+CD45RA+ and CD8+CD57- T cells (negatively) and neutrophils (positively). It is concluded that multiple and complex. intertwined relationships between HPA-axis hyperactivity and systemic immune stimulation participate in the pathophysiology or pathogenesis of major depression.