Immunity against mouse thymus‐leukemia antigen (TL) protects against development of lymphomas induced by a chemical carcinogen, N‐butyl‐N‐nitrosourea

Mouse thymus-leukemia antigens (TL) are aberrantly expressed on T lymphomas in C57BL/6 (B6) and C3H/He (C3H) mice, while they are not expressed on normal T lymphocytes in these strains. When N-butyl-N-nitrosourea (NBU), a chemical carcinogen, was administered orally to B6 and C3H strains, lymphoma development was slower than in T3 b -TL gene-transduced counterpart strains expressing TL ubiquitously as self-antigens, suggesting that anti-TL immunity may play a protective role. In addition, the development of lymphomas was slightly slower in C3H than in B6, which seems to be in accordance with the results of skin graft experiments indicating that both cellular and humoral immunities against TL were stronger in C3H than B6 mice. The interesting finding that B lymphomas derived from a T3 b -TL transgenic strain (C3H background) expressing a very high level of TL were rejected in C3H, but not in H-2K b transgenic mice (C3H background), raises the possibility that TL-specific effector T cell populations are eliminated and/or anergized to a certain extent by interacting with H-2K b molecules.