Longitudinal study of peritoneal defence mechanisms in patients on continuous ambulatory peritoneal dialysis (CAPD).

Peritoneal cellular and humoral defence mechanisms have been examined in a group of 16 patients over a nine-month period from the day of commencement of continuous ambulatory peritoneal dialysis (CAPD). Significant decreases in the levels of IgG, C3, and opsonic activity occurred with the passage of time in the over-night peritoneal dialysis effluent (PDE). The ability of PDE to inhibit in vitro growth of Staphylococcus epidermidis also decreased. The number of cells in the PDE and their ability to kill S. epidermidis decreased, although there was no significant change in their ability to ingest this organism. These results suggest that the immunological protection of the peritoneal cavity decreases with time, and this may account for the increase in the incidence of peritonitis with length of time on CAPD that some workers have reported.