Evaluation of the mechanism of zymosan-induced resistance to experimental peritonitis.

Three injections of intraperiotoneal (IP) zymosan-induced profound resistance to E. coli peritonitis in Sprague-Dawley rats. IP zymosan had minimal effects on organ weights and systemic phagocytic clearance ability, suggesting that this mode of administration had few systemic reticuloendothelial system (RES) effects. Hemoglobin (a known inhibitor of local phagocytosis) reduced the protection induced by zymosan, giving further evidence that IP zymosan acts locally. IP zymosan stimulation results in an initial marked influx of polymorphonuclear cells followed by a greater percentage replacement of mononuclear cells by the third day. Examination of these cells via chemiluminescence studies demonstrated that the phagocytic capacity of zymosan-stimulated peritoneal cells was markedly greater than the control group on a cell-for-cell basis. IP zymosan also gave some protection against intravenous (IV) E. coli, but IV zymosan did not significanly protect against IP E. coli. Possible mechanisms of action are discussed. These findings suggest that a technique of local RES stimulation could have a place in preparation of certain high-risk patients for elective abdominal surgery where peritoneal contamination is likely.