IN-VITRO AND IN-VIVO TUMORICIDAL PROPERTIES OF A PATHOGENIC FREE-LIVING AMEBA

The chemotactic and tumoricidal properties of the pathogenic/free-livi ng amoeba Acanthamoeba castellanii were examined in vivo and in vitro. A. castellanii trophozoites displayed strong positive chemotactic res ponses to human melanoma (OCM-1) and murine melanoma (D5.1G4) cells. A lthough the parasites typically invade and destroy the corneal epithel ium and stroma, positive chemotactic responses were not detected again st extracts of either of these corneal elements. In vitro studies reve aled that viable parasites, as well as cell-free parasite lysates, pro duced swift and extensive cytolysis of a wide variety of tumor cells. The tumoricidal properties of A. castellanii were examined in vivo and revealed that injection of viable parasites or cell-free parasite lys ates into progressively growing subcutaneous melanomas resulted in 83% and 53% reductions in the tumor masses compared with untreated contro ls. The feasibility of utilizing the tumoricidal properties of pathoge nic/free-living amoebae and their cell-free products in the treatment of drug-resistant or radioresistant tumors warrants further investigat ion.