INTERLEUKIN-10 RELEASE DURING ENDOTOXEMIA IN CHIMPANZEES - ROLE OF PLATELET-ACTIVATING-FACTOR AND INTERLEUKIN-6

Interleukin (IL-)10 has been demonstrated to inhibit endotoxin-induced production of a number of pro-inflammatory cytokines. The present stu dy sought to compare the appearances in the circulation of IL-10, IL-6 and IL-8, and to assess the roles of endogenously produced platelet-a ctivating factor (PAF) and IL-6 in IL-10 release during endotoxaemia i n chimpanzees. Intravenous injection of endotoxin (lot EC-5, 4 ng/kg, n = 8) induced a transient rise in serum IL-10 concentrations, peaking after 2 h (213 +/- 70 pg/ml; P < 0.05). No correlations existed betwe en peak IL-10 levels, and peak IL-6 and IL-8 levels. Neither infusion of the specific PAF antagonist TCV-309 (n = 4), nor infusion of a neut ralizing anti-IL-6 monoclonal antibody (n = 4) influenced endotoxin-in duced IL-10 release. IL-10 release elicited by injection of endotoxin is not mediated by PAF or IL6.