In vivo requirements for the immune recognition of L1210 leukemia cells by allogeneic T-lymphocytes.

The resistance of normal BALB/c mice (H-2d) against the L1210 Ha leukemia of DBA/2 mouse (H-2d) origin is due to the T-lymphocyte-dependent reaction towards DBA/2 multiple minor histocompatibility antigens (Mhas). These Mhas are displayed by the leukemic cells, though in a poorly immunogenic manner. The simultaneous presence of mitomycin C-inactivated DBA/2 leukocytes induces a significantly stronger T-lymphocyte-dependent reaction. This efficient presentation of target Mhas is restricted to Ia+ leukocytes. Their presence significantly increases BALB/c resistance, even when they are injected 3 days after the L1210 Ha challenge.