Cocaine inhibits human neutrophil phagocytosis and phagolysosomal acidification in vitro

Cocaine, used intravenously, increases the risk of infections, but its effe cts on neutrophil phagocytosis have not been examined in vitro. Human neutr ophils were suspended in cocaine hydrochloride 0, 1, 10, 50, 100 or 200 mu g/ml in Hank's balanced salt solution to which was added a phagocytic meal of killed Saccharomyces cerevisiae stained with the pH indicator dye bromcr esol purple. Yeast per phagocytosing neutrophil and the percent neutrophils phagocytosing yeast were reduced in neutrophils treated with cocaine 100 a nd 200 mu g/ml (P < 0.05). When examined for percent of yeast phagocytosed after 10 minutes, neutrophils treated with cocaine 1-200 mu g/ml demonstrat ed a decrease (P < 0.05). However, at 60 minutes only neutrophils treated w ith cocaine 50 and 100 mu g/ml still showed a decrease in percent of yeast phagocytosed. Phagolysosomal acidification was impaired in neutrophils trea ted with 50, 100 and 200 mu g/ml cocaine. Thus, cocaine inhibits neutrophil phagocytosis and phagolysosomal acidification in vitro, offering a reason for cocaine users/ abusers to have impaired host defense and to be potentia lly at higher risk for infections.