Nigericin is an antibiotic derived from Streptomyces “Nig-1”. It is the potassium ionophore and H+/K+ exchanger. It is shown to be highly effective as an ionophore for Pb(2+). Thus, nigericin may be more useful than monensin in the treatment of Pb intoxication. Nigericin induced mitochondrial membrane hyperpolarization. Malignant characteristics of human glioma cells were markedly suppressed by nigericin treatment in vivo. Nigericin induces cell death and promotes the maturation and release of IL-1beta in lipopolysaccharide (LPS)-primed monocytes and macrophages. The mechanism of induction of apoptosis by nigericin is most probably to decrease intracellular pH.