Immunological defenses in CAPD

The high peritonitis rate of a subgroup of patients on continuous ambulatory peritoneal dialysis (CAPD) may be due to alterations of peritoneal defense mechanisms, i.e. opsonization, phagocytosis and bacterial killing. It has been demonstrated that peritonitis incidence and in vitro opsonization of bacteria are related to the concentration of IgG in the dialysate and to the ability of macrophages to produce fibronectin. In addition, a decreased macrophage bactericidal activity is found in those with a high incidence of peritonitis; intracellular survival of microorganisms may, therefore, occur despite intact phagocytosis. A disturbance in the release of lymphokines and monokines in some CAPD patients may also reduce the ability of peritoneal macrophages to kill bacteria. On the basis of these defects, which involve both humoral and cellular defense mechanisms, it may be possible to treat these patients using IgG and interferon-alpha intraperitoneally.