IGG GLYCATION AND FUNCTION DURING CONTINUOUS AMBULATORY PERITONEAL-DIALYSIS

IgG in dialysate may have an important role in anti-infection mechanis ms during continuous ambulatory peritoneal dialysis (CAPD). As Fc frag ment oligosaccharidic chains are crucial for IgG effector functions, w e have tested the hypothesis that IgG glycation might occur during CAP D and modify IgG properties. Purified normal IgG was incubated with gl ucose solutions of different concentrations and pH. Separation of glyc ated IgG was performed by affinity chromatography. Complement activati on (C3c deposition) and phagocytosis by polymorphonuclear leucocytes ( PMN) were studied in vitro using Staphylococcus aureus Wood (STAW) as antigen. In addition, we compared the percentages of glycated IgG in I ge purified from sera and dialysates of 12 CAPD patients. The percenta ge of glycated IgG after in vitro incubation of normal IgG with glucos e solutions was directly proportional to glucose concentrations, incub ation time and pH. Glycated IgG anti-STAW induced a higher C3c deposit ion than non-glycated IgG anti-STAW (C3c/IgG (mean +/- SD) 0.96 +/- 0. 06 vs 0.79 +/- 0.08; P=0.027). PMN phagocytosis was not affected by Ig G glycation. The percentages of glycated IgG in dialysates of CAPD pat ients were greater than those in corresponding sera (5.38 +/- 2.36% vs 4.56 +/- 2.47%; P=0.006). It is concluded that IgG glycation may take place in the peritoneal cavity during CAPD and lead to enhanced compl ement activation. This could explain the high degree of complement act ivation previously described in dialysate of CAPD patients and might t heoretically result in a reduction of complement factors available in dialysate for adequate anti-infection mechanisms.