Ionophore-induced functional changes in macrophages.

Ca ionophore A 23187 and valinomycin known to induce Ca2+ influx, i.e. K+ efflux, appeared to induce activation-related changes in rat peritoneal macrophages (PM) at 10(-5)-10(-7) M concentrations as revealed by aggregation, nitro blue tetrazolium (NBT) reduction, superoxide anion production as well as beta glucuronidase release; however, lactate dehydrogenase (LDH) activity was measured in supernatants only after treatment with 10(-5) M of A 23187. The PM-activating effect of A 23187 was abolished in the presence of 5 mM EGTA, whereas the activating effect of K ionophore did not depend on the extracellular Ca2+. Fc receptor (FcR) mediated incorporation, intracellular killing as well as the antibody dependent cytotoxicity (ADCC) were markedly inhibited upon incubation with Ca ionophore or valinomycin. C3bR mediated phagocytosis was found to be more resistant to the cation transport affecting drugs. The impairment of effector functions was elicited by nontoxic concentrations of ionophores, however, their inhibiting effects did not require extracellular Ca2+ at the time of ionophore-exposition.