Surface Sulphydryl Groups and Phagocytosis-Associated Oxidative Metabolic Changes in Human Polymorphonuclear Leucocytes

Summary. The role of surface sulphydryl (-SH) groups of human polymorphonuclear leucocytes on phagocytosis and. phagocytosis-associated oxidative metabolic changes was studied. p-Chloromercurybenzene sulphonic acid, a surface -SH group inhibitor, had no effect on phagocytosis, superoxide production during phagocytosis, or killing of S. aureus by the leucocytes, while it inhibited phagocytosis-associated stimulation of hexose monophosphate pathway activity and H₂O₂ production. In contrast, N-ethylmaleimide, which inhibits both intracellular and surface -SH groups, inhibited phagocytosis and phagocytosis-associated oxidative metabolic changes. p-Chloromercurybenzene sulphonic acid also inhibited the stimulation of hexose monophosphate path-way activity by exogenous H₂O₂, suggesting a regulatory role of plasma membrane on the pathway's activity in human polymorphonuclear leucocytes. The results also suggest that: (1) superoxide production is the primary event of oxidative metabolic changes during phagocytosis, (2) superoxide plays an important role in the killing of S. aureus, and (3) the hexose monophosphate pathway plays a primary role in producing NADPH for H₂O₂ production from superoxide.