Inhibition of phagocytosis by a middle molecular fraction from ultrafiltrate.

The in vitro phagocytic activity of normal human blood was maximally inhibited by an uremic toxin isolated by Sephadex G 15 column chromatography from the ultrafiltrate obtained during a sequential hemodiafiltration procedure in an anephric patient. The phagocytic activity of the blood was studied by measuring the labelled CO2 production from glucose metabolism during the phagocytosis of latex, zymosan and inulin; phagocytosis was not influenced by urea levels of 4 g/l and creatinine levels of 15 mg/100 ml, whereas it was inhibited for 59% by uremic serum and for 90% by a D fraction. The D fraction blocking phagocytosis is of the so-called middle molecular weight range; the presumed molecular weight is between 113 and 1029; the elution volume Ve is 25.28/ml and the available distribution coefficient KAV 0.52.