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 antigen presentation capacity (APC), interleukin-1 (IL-1) expression, and immune-associated (Ia) antigen expression and abscess formation were determined following cecal ligation and puncture. APC and IL-1 expression were measured by coculture with a T-helper cell clone and by measuring subsequent proliferation. Ia expression was determined in blood, peritoneal Mphi, and splenocytes using anti-Ia monoclonal antibody stain and flow cytometric analysis. Significant reductions in both Ia expression and APC were found 1 and 4 days after CLP with no change in IL-1 expression. Muramyl dipeptide, which enhances Mphi phagocytosis, partially abrogated the depression in antigen presentation but did not affect Ia expression. Peritoneal Mphi Ia expression and APC, but not IL-1 expression, were depressed after experimental peritonitis. The recovery of Mphi function by day 14 coincides with clinical recovery and abscess formation, and restoration of early Mphi depression may improve outcome.