Periodic elevation of complement activation products in peritoneal dialysis effluent

Peripheral white blood cells (WBCs) of chronic ambulatory peritoneal dialysis (CAPD) patients show a reduced expression of chemotactic receptors and a desensitization to chemotactic factor induced events. Chronic complement activation has been suggested as a cause of such phenomena, resulting from either uremia, the indwelling peritoneal catheter, and/or dialysis fluid stimulation. The presence of complement activation products in peritoneal dialysis effluent was assessed by longitudinal measurement of C3bi in eight patients over a 6 to 8 month period, while peritoneal polymorphonuclear leukocyte (PMN) and monocyte CR3 and C5a receptor expression was quantitated by flow cytometry. In six of eight patients, C3bi levels were stable over time and usually measured less than 5 micrograms/ml. Two other patients showed periodic elevation of C3bi, which was not associated temporally with peritonitis. Further study is required to identify the origin of such activated complement components within the peritoneal cavity. However, no correlation was found between dialysate C3bi levels and peritoneal PMN or monocyte expression of CR3 or C5a receptors. Furthermore, the incidence of peritonitis for the two individuals with elevated C3bi was discordant (1 episode/8 patient months vs. 0 episodes/32 patient months), suggesting little or no relationship between these parameters.