INCREASED PLASMA-CONCENTRATIONS OF INTERLEUKIN-6, SOLUBLE INTERLEUKIN-6, SOLUBLE INTERLEUKIN-2 AND TRANSFERRIN RECEPTOR IN MAJOR DEPRESSION

Recently, it was found that major depression may be accompanied by sig nificant changes in cell-mediated and humoral immunity. The purpose of this study was to investigate the plasma concentrations of interleuki n (IL)-6, soluble IL-6 receptor (sIL-6R), sIL-2R and transferrin recep tor (TfR) in patients with major depression in an acute phase of illne ss, in remission and during antidepressive treatment. Plasma concentra tions of IL-6, sIL-6R, sIL-2R and TfR were significantly higher in maj or depressed subjects than in healthy controls. In major depressed sub jects, but not in normal controls, there were significant positive cor relations between the plasma concentrations of IL-6 and sIL-6R, IL-6 a nd sIL-2R, IL-6 and TfR, and between sIL-2R and TfR. Subchronic treatm ent with antidepressive drugs, such as fluoxetine or tricyclic antidep ressants, did not significantly affect plasma IL-6, sIL-6R, sIL-2R or TfR. The latter did not significantly differ between major depressed p atients in an acute phase of illness or in complete clinical remission . It is suggested that: (1) a coordinated and upregulated production o f IL-6, sIL-6R, sIL-2R and TfR may constitute a trait marker of major depression; and that (2) an upregulated production of IL-6 may represe nt a contributing factor to the various immune disorders encountered i n major depression and maybe to the pathophysiology or pathogenesis of that illness.