INTERLEUKIN-6 MEDIATES HOST-DEFENSE RESPONSES INDUCED BY ABDOMINAL-SURGERY

Background. Cytokines have been implicated as pivotal mediators of the host defense reaction. In patients undergoing surgery we investigated the relationship between such mediators and postoperative host defens e responses. Methods. Tumor necrosis factor (TNF) was determined with an immunoradiometric assay, interleukin (IL) -6 by a Bg-cell bioassay, and endotoxin by a chromogenic limulus lysate assay. C-reactive prote in, alpha1-antitrypsin, and alpha2-macroglobulin were quantified by ne phelometric assay. Results. In 19 consecutive patients undergoing panc reaticoduodenectomy, a large increase in portal, and a significantly l ower increase in peripheral, IL-6 levels was observed. No significant increase in TNF levels was noted. Fever developed in 16 patients withi n 24 hours (84%). The highest peripheral IL-6 levels correlated logari thmically (R = 0.59; p = 0.0039) with the peak body temperatures. C-re active protein levels correlated with IL-6 levels (R = 0.49; p = 0.020 ). Increased IL-6 levels were observed in all nine patients undergoing either hemihepatectomy, breast reduction, or extensive breast reconst ruction; however, only patients undergoing hemihepatectomy had endotox emia. Conclusions. We conclude that abdominal surgery causes acute rel ease of IL-6, but not TNF, in the portal circulation. IL-6 seems to be a major endogenous mediator of fever and the acute-phase response. Th e presence of endotoxin might be synergistic but is not obligatory for the host defense response after surgical trauma.