Interaction between erythropoietin and peripheral polymorphonuclear leukocytes in continuous ambulatory dialysis patients

The effect of erythropoietin (EPO) on the oxidative stress (OS) and inflammation caused by polymorphonuclear leukocytes (PMNLs) in end-stage renal failure patients undergoing continuous ambulatory peritoneal dialysis (CAPD) was investigated in vivo and in vitro. The studies were performed on isolated PMNLs from peripheral blood of CAPD patients before and following 6 weeks of EPO treatment and from healthy controls. OS was expressed by the rate of superoxide release from phorbol 12-myristate 13-acetate (PMA) stimulated isolated PMNLs and the inflammatory state was evaluated by PMNL counts of the enrolled subjects. Following 6 weeks of EPO treatment in CAPD patients, both the rate of superoxide release from PMNLs and PMNL counts fell significantly when compared with the pretreatment values. In vitro incubation of PMNLs from CAPD patients with increasing amounts of EPO displayed a significant reduction in their rates of superoxide release. EPO, by direct interaction with PMNLs, attenuated their primed state, causing reduction in oxidative stress and inflammation.