Neutrophil toxicity of amphotericin B.

The toxicity of amphotericin B (AmB) for neutrophils and the protective effect of serum cholesterol were investigated. Neutrophils were exposed in vitro to varying concentrations of AmB. As judged by trypan blue exclusion, neutrophil viability decreased by 40% (P < 0.001) within 30 min of incubation in sterol-free buffer containing 5 mug of AmB per ml. In the presence of 4 mg of cholesterol per 100 ml in buffer, the AmB concentration could be increased to 50 mug/ml before significant (P < 0.01) neutrophil toxicity occurred. Hexose monophosphate shunt activity of neutrophils incubated in serum or cholesterol-containing buffer with 10 mug of AmB per ml was normal. These results suggest that serum contains a protective factor, probably cholesterol, which protects neutrophils in vitro from the toxic effects of AmB.