Generation of cytotoxic cells in absence of blastogenesis by mouse leukemic cells in mixed cultures

Primary virus induced murine leukemias and transplantable leukemic cell lines, originally induced by virus, chemical or physical agents, failed to stimulate normal spleen cells differing at the H 2 complex or at Mls locus in the one way mixed leukocyte culture. Lack of stimulation seems at least partially due to a nonspecific inhibitory effect since in a 'three party' culture system the leukemic cells interfered with the mixed leukocyte reaction (MLR) of normal allogeneic cells. Characterization of the leukemic cell populations used, according to their T or B cell origin, disclosed that in most cases T cell markers were present. Also, no Ia antigens were detected on leukemic cells. Furthermore, using a ⁵¹Cr release assay, leukemic cells could sensitize allogeneic normal lymphocytes to kill specifically normal as well as leukemic targets, even when no MLR was detected in parallel cultures.