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.