Peritoneal macrophages during peritonitis. Phenotypic studies.

The expression of a range of surface molecules/receptors that are important in the host response to infection and foreign antigens was examined using peritoneal macrophages isolated from patients on continuous ambulatory peritoneal dialysis (CAPD) with peritonitis. The macrophage phenotypic profile was compared with that of normal peripheral blood monocytes. Consistently there was increased expression by macrophages of CD14, ICAM-1 (CD54), Fc gamma RI (CD64), Fc gamma RII (CDw32), Fc gamma RIII (CD16), transferrin receptors (CD71) and tissue factor. Increased expression of MHC class II was marginally significant. There was no detectable expression of either the p55 (CD25) or p70 chains of the IL-2 receptor. The expression of the complement receptors, CR1 (CD35) and CR3 (CD11b, CD18), was reduced. The activity of well-known inflammatory cytokines, rather than uraemic molecules, can account for the phenotypic profile of these extravasated peritoneal macrophages. The results of this study indicate that peritoneal macrophages from CAPD patients with peritonitis display a phenotype consistent with them being in vivo-derived inflammatory macrophages, and that they are appropriate for use in studies of anti-inflammatory agents.