Properties of calcium ionophore-induced generation of superoxide anion by human neutrophils.

Exposure of human neutrophils to the calcium ionophore, A23187, eventuates in a time- and concentration-dependent generation of superoxide anion (O2-) in the presence but not absence of extracellular calcium. The selective requirement for calcium is demonstrated by the observation that magnesium caused a dose-related inhibition of A23187-stimulated O2- generation. Preincubation of neutrophils with cytochalasin B prior to their interaction with A23187 results in a significant enhancement of O2- production. The activity of the O2--generating system was maximum at 37 degrees C and was significantly curtailed at lower and higher temperatures. A23187-induced O2- generation was inhibited by the sulfhydryl reagents. N-ethyl maleimide (NEM) and iodoacetic acid (IA), and by the metabolic inhibitor 2-deoxy-D-glucose (2-DG) in the absence of glucose and cytochalasin B. Cyanide was inactive. Therefore, A23187 represents a useful pharmacologic probe for investigating the divalent cation and metabolic requirements of the neutrophil O2--generating system.