Effect of pyridoxal 5'-phosphate on human neutrophil aggregation in vitro

Pyridoxal 5'-phosphate inhibited polymorphonuclear leukocyte aggregation in vitro in a dose-dependent fashion at concentrations ranging from 0.5 to 0.001 mmol/l. At pyridoxal 5'-phosphate concentrations between 0.4 and 0.5 mmol/l mean inhibition of aggregation was about 50%-60%. In this range, and at lower pyridoxal 5'-phosphate concentrations, phorbol myristate acetate-activated polymorphonuclear leukocytes showed a normal increase in volume, whereas swelling was inhibited at higher concentrations of pyridoxal 5'-phosphate. Since pyridoxal 5'-phosphate can be administered as a vitamin to man without any relevant side-effects its role as a physiological anti-aggregant of polymorphonuclear leukocytes warrants further investigation.