Neutrophil function in patients on continuous ambulatory peritoneal dialysis.

Frequent and recurrent episodes of peritonitis are a major cause of morbidity in patients on continuous ambulatory peritoneal dialysis (CAPD). One factor contributing to this problem may be an abnormality of neutrophil function in these patients. We have therefore quantified phagocytosis and killing by circulating and peritoneal neutrophils from patients on CAPD with and without peritonitis. Circulating neutrophils from uninfected patients showed reduced phagocytosis of both Staphylococcus epidermidis and Candida guilliermondii because of an opsonic defect in CAPD serum and because of a defect of the neutrophils themselves. In contrast, phagocytosis by circulating and peritoneal neutrophils from patients with peritonitis was normal. Intracellular killing of C. guilliermondii was normal in all groups of neutrophils but killing of S. epidermidis, the organism most commonly isolated in CAPD peritonitis, was reduced. The possible mechanisms for the enhanced neutrophil activity seen in peritonitis, and for the decreased killing of S. epidermidis in contrast to normal killing of C. guilliermondii are discussed. A defect in killing of S. epidermidis may explain why peritonitis caused by this organism can be difficult to erradicate.