Relationship of IgG, C3 and Transferrin with Opsonising and Bacteriostatic Activity of Peritoneal Fluid from CAPD Patients and the Incidence of Peritonitis

Abstract

IgG, C3 and transferrin in peritoneal dialysis effluent of patients undergoing continuous ambulatory peritoneal dialysis (CAPD) were 1%-2% of those in serum. In contrast, the values in normal peritoneal fluid were not significantly different from those in serum. The three proteins correlated with each other in peritoneal dialysis effluent, but were independent of the amount in the corresponding patients' sera. There was also an overall inverse correlation between total protein in peritoneal dialysis effluent and time on CAPD during the first 6 months of treatment but not thereafter, which suggests that changes in membrane permeability occur during the early months. In peritoneal dialysis effluent, but not in normal peritoneal fluid, there was a correlation between opsonising capacity and IgG or C3 concentrations. An inverse correlation between opsonic activity of peritoneal dialysis effluent and frequency of peritonitis was also found. Peritoneal dialysis effluent permitted significantly faster multiplication of Staphylococcus epidermidis than sera or normal peritoneal fluid, and the growth rate correlated inversely with the transferrin levels in peritoneal dialysis effluent. Overall IgG, C3 and transferrin in peritoneal dialysis effluent are inadequate for optimal opsonising and bacteriostatic activity, and the peritoneal cavities of CAPD patients are therefore immunocompromised sites.