IMMUNIZATION AGAINST RAUSCHER MOUSE LEUKEMIA WITH TISSUE CULTURE MATERIAL.

Long-term monolayer cultures of mouse thymus and spleen cells, chronically infected with Rauscher virus, showed only a very attenuated leukemia-producing capacity. Material from these cultures prepared from normal BALB/ c mouse tissue was used to immunize isologous mice against subsequent challenge with fully active Rauscher virus. The centrifuged supernatant of the culture had some immunizing properties. However, the most efficient protectionwas obtained when cell suspensions from these cultures were used in the form of a series of three intraperitoneal and intramuscular injections and onebooster injection.