CHANGES IN ENDOTOXIN-INDUCED CYTOKINE PRODUCTION BY WHOLE-BLOOD AFTERIN-VIVO EXPOSURE OF NORMAL HUMANS TO ENDOTOXIN

Whole blood of 6 healthy subjects, who were intravenously injected wit h lipopolysaccharide (LPS, 2 ng/kg), was stimulated ex vivo with LPS ( 10 ng/mL). Three and 6 h after injection of LPS, whole blood produced less tumor necrosis factor-alpha (TNF), interleukin (IL)-1 beta, IL-6, and IL-10 (all P < .05). By contrast, the production of IL-1 receptor antagonist was enhanced after LPS injection (P <.05). Plasma obtained 2 h, but not 1 h, after in vivo administration of LPS showed a dose-d ependent inhibition of TNF, IL-1 beta, acid IL-6 production by LPS-sti mulated whole blood from 6 other healthy donors not previously exposed to LPS, while the production of IL-10 and IL-1 receptor antagonist we re not or were marginally influenced. LPS tolerance represents a purpo seful adaptation of the host, rather than a generalized hyporesponsive ness, and is at least partly mediated by soluble factors produced with in 2 h after previous exposure to LPS.