Time course of cytokine levels in sepsis.

In severe sepsis, a network of proinflammatory cytokines (TNF, IL-1 beta, IL-6, IL-8) is activated and blood levels of these cytokines are elevated, albeit inconsistently and with large individual variations. In addition, elevated blood levels of anti-inflammatory cytokines (IL-10), as well as of soluble cytokine receptors (sTNF-RI and II, IL-1ra), have been found. They seem to have a regulatory function in the host response. Levels of TNF and IL-6 are usually highest at the time of admission, whereas the time course of IL-1 beta levels (when detectable) can vary considerably. Limited data on IL-8 levels suggest that they may remain elevated for longer periods. Elevated levels of sTNFR and IL-1ra may also persist for a prolonged period of time. The pathogenetic significance of these observations is still unclear, but persistingly high levels of proinflammatory cytokines may be associated with organ failure and mortality.