Phagocytosis of the protozoon Tetrahymena pyriformis as an endpoint in the estimation 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 phagocytic activity of this protozoon was studied in vivo using heat-inactivated yeast stained with carmine after exposing the cultures for 1 hour to different 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 the phagocytic activity. Cocaine hydrochloride and crack caused a decrease of 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 phagocytic activity. Crack produced an extensive decrease in phagocytosis, compared to equal concentrations of cocaine hydrochloride. These results suggest a possible relationship between cocaine abuse and the suppression of phagocytosis that may contribute to the impairment of immunity in drug misusers.