High‐ and low‐leukemogenic variants of the radiation leukemia virus (RadLV) differ in ability to induce tumor‐specific immune suppression

Adult C57BL/6 mice inoculated intrathymically (i.t.) with the highly leukemogenic variant of the radiation leukemia virus (A‐RadLV) develop suppressor cells capable of specifically abrogating a potential anti‐tumor cytotoxic response in vitro. Suppressor cells were generated directly by the virus, independently of an initiation of a leukemogenic process. Inoculation of C57BL/6 animals with the low leukemogenic D‐RadLV variant did not result in suppressor cell generation. It is proposed that induction of tumor‐specific immune suppression by A‐RadLV is essential for tumor progression, and the leukemogenic activity of D‐RadLV is attributed to its inability to recruit suppressor cells.