Simultaneous demonstration of phagocytosis-connected oxygen consumption and corresponding NAD(P)H oxidase activity: Direct evidence for NADPH as the predominant electron donor to oxygen in phagocytizing human neutrophils

Phagocytosis-connected oxygen consumption by human neutrophils and corresponding NAD(P)H oxidase were measured by an oxygen electrode with sequential additions of opsonized zymosan, Renex 30 (0.067%), and NAD(P)H. At a concentration of 0.15 mM substrate, NADPH oxidase activity of stimulated neutrophils was twice that required to account for accompanying oxygen consumption, and was about 20 times higher than that activity obtained from resting cells. NADH oxidase activity of phagocytizing cells, however, was negligible at the same concentration of substrate. With high recovery of oxidase activity, these results strongly suggest that NADPH is the dominant electron donor to oxygen in phagocytizing human neutrophils.