[Directed attacks on the specific activity of leukemia cells]

Different means of attenuating the leukemogenic activity were studied comparatively with a continuous strain of bone marrow cells derived from mice infected with Rauscher leukemia virus. Treatment of leukemic cells with neuraminidase, like their cultivation at suboptimal temperature resulted in a complete loss of leukemogenic activity, as evidenced by 100% survival of experimental animals and the absence of splenomegaly. In parallel experiments with concanavallin A and 5-bromdeoxyuridine treatment, development of splenomegaly was retarded and lethality of the animals reduced by 70 and 20%, rnd 20%, respectively. These results permit to raise the problem of using the above-memtioned methods for the attenuation of leukemogenic activity as an approach to prepare material with the immunizing activity.