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Antimicrobial activities of dialysate-elicited and resident human peritoneal macrophages
Abstract:
Recent studies of the antimicrobial capacity of peritoneal macrophages (PM phi) isolated from patients undergoing chronic peritoneal dialysis have raised the question of whether these cells might be analogous to stimulated or activated murine PM phi. To explore this possibility, we compared PM phi from these patients (dialysate-elicited PM phi) with PM phi obtained from women undergoing laparoscopy (resident PM phi) 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 PM phi was 4.7 X 10(5) cpm, that of resident PM phi was only 1.3 X 10(5) cpm (P less than 0.05). In a lucigenin-enhanced chemiluminescence assay, dialysate-elicited PM phi again generated significantly greater chemiluminescence than did resident PM phi, suggesting that dialysate-elicited PM phi 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 PM phi killed 17% of cell-associated blastospores compared with only 1.5% killing by resident PM phi (P less than 0.05). These investigations led us to conclude that results of studies of the functional activity of dialysate-elicited PM phi cannot necessarily be extrapolated to resident PM phi and that dialysate-elicited PM phi do in some respects behave as stimulated or activated cells.
Insights
Peritoneal macrophages (PM phi) from dialysis patients show enhanced antimicrobial activity compared to resident PM phi. These findings suggest dialysate-elicited PM phi function as activated cells, impacting research extrapolation.
Area of Science:
- Immunology
- Cell Biology
- Nephrology
Background:
- Studies on peritoneal macrophages (PM phi) from chronic peritoneal dialysis patients raise questions about their activation status.
- Comparison is needed between dialysate-elicited PM phi and resident PM phi for functional insights.
Purpose of the Study:
- To compare the phagocyte function of dialysate-elicited PM phi from dialysis patients with resident PM phi from healthy women.
- To determine if dialysate-elicited PM phi exhibit characteristics of stimulated or activated cells.
Main Methods:
- In vitro assays of phagocyte function, including bacterial phagocytosis, luminol- and lucigenin-enhanced chemiluminescence, and intracellular candidicidal activity.
- Comparison of chemiluminescence responses and O2- production capacity between the two PM phi groups.
- Assessment of killing capacity against Candida blastospores.
Main Results:
- Bacterial phagocytosis was similar between dialysate-elicited and resident PM phi.
- Dialysate-elicited PM phi demonstrated significantly higher chemiluminescence responses (luminol and lucigenin) than resident PM phi, indicating increased O2- production.
- Dialysate-elicited PM phi exhibited significantly greater intracellular candidicidal activity (17% killing) compared to resident PM phi (1.5% killing).
Conclusions:
- Dialysate-elicited PM phi display enhanced antimicrobial functions, particularly in chemiluminescence and candidicidal activity, suggesting they behave as stimulated cells.
- Functional data from dialysate-elicited PM phi studies may not be directly extrapolated to resident PM phi.
- Peritoneal dialysis may induce a state of activation in peritoneal macrophages.