Elevated serum interleukin-6 (IL-6) and IL-6 receptor concentrations in posttraumatic stress disorder following accidental man-made traumatic events

Background: Recently, it has been reported that serum interleukin-1 beta (I L-1 beta), but not soluble IL-2 receptor (sIL-2R), concentrations were sign ificantly higher in patients with posttraumatic stress disorder (PTSD) than in normal volunteers, and that psychological stress in humans is associate d with increased secretion of proinflammatory cytokines, such as IL-6. Methods: The aim of the present study was to examine the inflammatory respo nse system in patients with PTSD through measurements of serum IL-6, sIL-6R , sgp130 (the IL-6 signal transducing protein), sIL-1R antagonist (sIL-1RA; an endogenous IL-1 receptor antagonist), CC16 (an endogenous anticytokine) , and sCD8 (the T suppressor-cytotoxic antigen). Results: Serum IL-6 and sIL-6R, but not sgp130, sIL-RA, CC16, or sCD8, conc entrations were significantly higher in PTSD patients than in normal volunt eers. Serum sIL-6R concentrations were significantly higher in PTSD patient s with concurrent major depression than in PTSD patients without major depr ession and normal volunteers. There were no significant relationships betwe en serum IL-6 or sIL-6R and severity measures of PTSD. Conclusions: The results suggest that PTSD is associated with increased IL- 6 signaling. It is hypothesized that stress-induced secretion of proinflamm atory cytokines is involved in the catecholaminergic modulation of anxiety reactions. (C) 1999 Society of Biological Psychiatry.