The inactivation in vitro of transplantable myeloid and lymphoid mouse leukemic cells by antibodies produced in a foreign host species.

Natural susceptibility and innate resistance to the development of spontaneous, induced, or transplantable neoplasms are ascribed to differ ences in genetic constitution (4, 7, 14, 16).' The extent to which specific immunogenic processes participate is little understood. The evidence that malignant and normal cells differ in genie com position (5, 9, 10) makes it probable that the antigenie components of these cells likewise should dif fer. Indeed, it has been shown for mouse leukemia that the injection of leukemic cells results for mice of the same inbred strain in a state of immunity (11) and for animals of heterologous species in the production of antibodies (2,12,16). More recently, a variety of immunologie studies has been con cerned with malignant cells and their components (1-3). It was with the recognition that immuno logie technics make possible more precise informa tion than the application of histopathological and chemical methods that the present investigation was undertaken to demonstrate antigenic differ ences in the constituents of normal and leukemic cells. It is the purpose of this paper to record the results of experimental studies which show (a) the ability of specific preformed antibodies derived from the rabbit to neutralize the leukemogenic ef fect of leukemic cells on transfer to susceptible in bred mice of known genetic constitution and (6) differences in the antigenic components of leu-