COMPLEMENT IN SERUM AND DIALYSATE IN CHILDREN ON CONTINUOUS AMBULATORY PERITONEAL-DIALYSIS

Objective: During continuous ambulatory peritoneal dialysis (CARD), ac tivation of complement in the peritoneal cavity may theoretically occu r, with inappropriately high or low levels of certain complement facto rs in dialysate as a consequence. In a group of children on CAPD, it w as tested whether levels of a number of complement factors in dialysat e were in the range that was predicted on the basis of their molecular weight. Design: Serum and dialysate levels of C1q, C3, C4, C3d, B, D, and P were measured after a night dwell in children on CARD. Simultan eously, four non-complement proteins (beta 2-microglobulin, albumin, I gG, and alpha 2-macroglobulin) were also measured in dialysate and ser um. Assuming a linear relationship between the log base 10 of the dial ysate/serum ratio of these non-complement proteins and the log base 10 of their molecular weight, the expected ratios of all complement fact ors were determined. The differences between actual and predicted rati os were tested using a modified t-test, taking into account the inaccu racy of the estimate. Setting: University hospital. Patients: A group of 14 children on CAPD, with a median age of 7.8 years (range 2.1 - 13 .2). These children had been on CARD for a median period of 42.4 month s (range 0.4 - 89.1). Results: The ratios of factor D (p < 0.001) and C3d (p = 0.035) were elevated, whereas those of C3 (p < 0.001), C4 (p < 0.001), and factor P (p = 0.012) were decreased. Conclusions: Relati vely low dialysate/serum ratios of C4, C3, and factor P could be cause d by intraperitoneal consumption of complement. High levels of C3d are compatible with this. High dialysate/serum ratios of factor D indicat e intraperitoneal production of factor D. These results provide eviden ce for activation of complement in the peritoneal cavity in children o n CARD. A further reduction of already low levels of complement factor s in dialysate as a result of this may impair host defense.