Effect of peritoneal dialysis effluent on superoxide anion production by polymorphonuclear neutrophils

Peritoneal dialysis effluent (PDE) contains at least 2 factors capable of affecting superoxide generation by polymorphonuclear neutrophils (PMN) in response to both particulate and soluble stimuli. A low molecular weight fraction (< 1.2 kD) enhanced the response to the chemotactic peptide fMLP and to preopsonised Staphylococcus epidermidis and Candida guilliermondii. A higher molecular weight fraction (> 1.2 kD) inhibited superoxide production in response to phorbol myristate acetate (PMA). The effects of PDE were dose dependent over the range of 10-70% (v/v) and simply augmented and reduced the dose-response curve to fMLP and PMA, respectively. There was no alteration in the concentration of stimulus required to give maximal superoxide production in either case. These data suggest that factors capable of affecting superoxide production by PMN accumulate in uraemia and are removed from the circulation into dialysis fluid.