Opsonic activity of intravenous immunoglobulin preparations against Staphylococcus epidermidis

Peritoneal dialysis effluent collected from patients undergoing continuous ambulatory peritoneal dialysis had no opsonic activity against Staphylococcus epidermidis and contained low concentrations of IgG and C3 (roughly equal to those found in 0.5% normal human serum). An intravenous immunoglobulin preparation that showed no opsonic activity against the same organism, on its own or when added to balanced salt solution or peritoneal dialysis fluid, showed good activity when combined with peritoneal dialysis effluent. This was probably due to the presence of low concentrations of C3 in the effluent as prior heat inactivation at 56 degrees C for 30 minutes eliminated any opsonic activity in the immunoglobulin-dialysis effluent mixture. Examination of a range of immunoglobulin preparations showed that their opsonic activity for S epidermidis in the absence of complement varied considerably. Luminol dependent chemiluminescence was unsatisfactory as a method for detecting complement independent immunoglobulin mediated opsonisation. Intravenous immunoglobulin preparations may be useful in boosting the peritoneal defences of those patients undergoing continuous ambulatory peritoneal dialysis (CAPD) who suffer from repeated intraperitoneal infections.