STUDIES ON IMMUNITY TO LEUKEMIA L1210 IN MICE.

Abstract

Studies are described on immunity to L1210 (a DBA/2 leukemia) in DBA/2 and CDBA F1 hybrid (BALB/cAn ♀ × DBA/2♂) male animals. Immunity was detectable in CDBA animals, either following treatment of advanced leukemia L1210 with 3′,5′-dichloroamethopterin or following pretreatment with x-radiated L1210 splenic suspensions from DBA/2 mice. Under the same conditions any immune response in DBA/2 mice was doubtful. Pretreatment with normal or x-radiated normal DBA/2 spleen did not protect CDBA animals against L1210 challenge. DBA/2 skin grafts were rejected by a proportion of normal CDBA animals and by CDBA animals preimmunized with L1210. The rejections were late—about 140 days for normal animals and 93 days for the immune mice. Control grafts of CDBA or of BALB/c skin were uniformly accepted. Possible explanations for the unexpected rejection of DBA/2 skin grafts by the F1 hybrids are considered. The variation in response to L1210 between DBA/2 and CDBA animals is discussed with reference to possible approaches for altering the host-tumor relationship so as to augment the effect of chemotherapy.