Antimicrobial activities of dialysate-elicited and resident human peritoneal macrophages

Abstract

Recent studies of the antimicrobial capacity of peritoneal macrophages (PMΦ) isolated from patients undergoing chronic peritoneal dialysis have raised the question of whether these cells might be analogous to stimulated or activated murine PMΦ. To explore this possibility, we compared PMΦ from these patients (dialysate-elicited PMΦ) with PMΦ obtained from women undergoing laparoscopy (resident PMΦ) in several in vitro assays of phagocyte function. Although bacterial phagocytosis by cells from both groups of donors was similar, significant differences were found in their chemiluminescence responses to opsonized zymosan. Although the mean peak luminol-enhanced chemiluminescence response of dialysate-elicited PMΦ was 4.7 x 105 cpm, that of resident PMΦ was only 1.3 x 105 cpm (P < 0.05). In a lucigenin-enhanced chemiluminescence assay, dialysate-elicited PMΦ again generated significantly greater chemiluminescence than did resident PMΦ, suggesting that dialysate-elicited PMΦ have a relatively increased capacity for O2- production. Using a fluorochrome microassay to assess the intracellular candidicidal activities of these cells, we found that dialysate-elicited PMΦ killed 17% of cell-associated blastospores compared with only 1.5% killing by resident PMΦ (P < 0.05). These investigations led us to conclude that results of studies of the functional activity of dialysate-elicited PMΦ cannot necessarily be extrapolated to resident PMΦ and that dialysate-elicited PMΦ do in some respects behave as stimulated or activated cells.