ALTERATION OF MONONUCLEAR CELL IMMUNE-ASSOCIATED ANTIGEN EXPRESSION, INTERLEUKIN-1 EXPRESSION, AND ANTIGEN PRESENTATION DURING INTRAABDOMINAL INFECTION

Intact peritoneal macrophage (Mphi) function is critical to successful localization of intra-abdominal infection. Peritoneal macrophage anti gen presentation capacity (APC), interleukin-1 (IL-1) expression, and immune-associated (Ia) antigen expression and abscess formation were d etermined following cecal ligation and puncture. APC and IL-1 expressi on were measured by coculture with a T-helper cell clone and by measur ing subsequent proliferation. Ia expression was determined in blood, p eritoneal Mphi, and splenocytes using anti-Ia monoclonal antibody stai n and flow cytometric analysis. Significant reductions in both Ia expr ession and APC were found 1 and 4 days after CLP with no change in IL- 1 expression. Muramyl dipeptide, which enhances Mphi phagocytosis, par tially abrogated the depression in antigen presentation but did not af fect Ia expression. Peritoneal Mphi Ia expression and APC, but not IL- 1 expression, were depressed after experimental peritonitis. The recov ery of Mphi function by day 14 coincides with clinical recovery and ab scess formation, and restoration of early Mphi depression may improve outcome.