Phagocytosis of the protozoon Tetrahymena pyriformis as an endpoint in theestimation of cocaine salt and cocaine freebase toxicity

Cells of the ciliated protozoon Tetrahymena pyriformis strain W, grown in a peptone-yeast medium, usually contain many phagocytic vacuoles. The phagoc ytic activity of this protozoon was studied in vivo using heat-inactivated yeast stained with carmine after exposing the cultures for 1 hour to differ ent doses of cocaine hydrochloride or cocaine freebase (crack) (0.5, 1 or 2 mg/100 ml of protozoan culture). The number of vacuoles formed indicated t he phagocytic activity. Cocaine hydrochloride and crack caused a decrease o f the phagocytic activity of the protozoon (p < 0.05) when compared to the control cultures. Furthermore, the two chemical forms of cocaine, salt and free-base respectively caused quantitatively different effects on the phago cytic activity. Crack produced an extensive decrease in phagocytosis, compa red to equal concentrations of cocaine hydrochloride. These results suggest a possible relationship between cocaine abuse and the suppression of phago cytosis that may contribute to the impairment of immunity in drug misusers.