Background: Peritonitis is a common complication of end stage renal failure (ESRF) patients receiving continuous ambulatory peritoneal dialysis (CAPD). Peritoneal macrophage may participate in the activation of specific T cells and in the generation of local cell-mediated immunity to various pathogens. The purpose of this study is to investigate the possible role of macrophage in CAPD patients with peritonitis.
Methods: We evaluated the expression of Fas receptor (CD95), ICAM-1 (CD54), CD25, and CD69 by two-color flow cytometry on extravasted macrophages from 16 ESRF patients on CAPD with peritonitis (peritonitis-positive) and compared them to 11 ESRF patients on CAPD without peritonitis (peritonitis-negative) and normal controls.
Results: We found an increased expression of CD95, CD54, and CD25 on macrophage in peritonitis-positive group compared to controls (all p < 0.001). In the peritonitis-positive group, the CD95 expression was significantly higher than that of the peritonitis-negative group (p < 0.001). The expression of CD54, CD25, and CD69, however, was not significantly different between the peritonitis-positive and peritonitis-negative CAPD subgroups.
Conclusion: We found an abnormally increased percentage of macrophage-expressing Fas receptor and ICAM-1, and the percentage of CD95+ macrophage, but not those of other markers, were increased among the subset of CAPD patients with peritonitis. The later finding suggests that this macrophage phenotype is associated with peritonitis occurring in CAPD.