Depolarization blunts the oxidative burst of human neutrophils. Parallel effects of monoclonal antibodies, depolarizing buffers, and glycolytic inhibitors.

Abstract

The anti-neutrophil mAb PMN 7C3 and IIC4 inhibited the respiratory burst of neutrophils as measured by the generation of superoxide anion or hydrogen peroxide in response to PMA, serum-treated zymosan, and FMLP. To examine the effect of these mAb on neutrophil transmembrane potential, a fluorescent probe was used in a continuous assay. Compared with control cells, antibody-treated neutrophils were partially depolarized at rest and had a blunted response when stimulated. The F(ab)2 fragment of PMN 7C3 had similar effects on both the respiratory burst and transmembrane potential, whereas the Fab fragment did not. The unrelated antineutrophil mAb 31D8 had no effect on either the respiratory burst or on transmembrane potential. Neutrophils suspended in high potassium buffers also exhibited partial depolarization of the resting cell membrane and a blunted depolarization response to stimuli and produced less superoxide anion and hydrogen peroxide in response to stimuli than did control cells in physiologic buffer. Exposure of neutrophils to 2-deoxy-D-glucose resulted in dose- and time-dependent depression of the respiratory burst. 2-Deoxy-D-glucose also caused depolarization of the resting membrane and impaired subsequent stimulus-induced depolarization. Similar effects were seen with addition of iodoacetamide or depletion of glucose. The parallel effects of anti-neutrophil mAb, depolarizing buffers, and glycolytic inhibitors on both neutrophil membrane depolarization and activation of the respiratory burst indicate a close association between these two events. The evidence suggests that the inhibitory effects of these antibodies are mediated through partial membrane depolarization which interferes with signal transduction on subsequent stimulation of the cells. The impairment in oxidative responses to phorbol esters as well as to receptor-dependent activating agents points to interruption at a distal step, e.g., subsequent to Ca2+ mobilization.