Common leukemia-associated antigen of DBA/2 mouse leukemia detected by tumor rejection and complement-dependent cytotoxicity assays.

A cytotoxic antibody for L1210 leukemia cells was found in the (C57BL/6 x DBA/2)F1 (BDF1) mice immunized with L1210 leukemia cells infected with ts mutant of HVJ (HVJ-pi) and challenged several times with uninfected L1210 leukemia cells. These immune mice fell into two categories; high and low responders regarding the titer of cytotoxic antibody produced. The antigen defined by this cytotoxic antibody was present on leukemia cells originating in DBA/2 mice but not on leukemia induced by passage-A Gross virus or spontaneous mammary tumors. This serological cross-reactivity among L1210, P388, and L5178Y leukemia cells has been substantially confirmed by the observation of cross protection against challenge with DBA/2 leukemia cells in immune BDF1 mice. These findings strongly suggested the presence of a common DBA/2 leukemia-associated antigen different from known cell-surface antigens of murine leukemia. The results obtained in the present work also demonstrated the great efficacy of non-cytopathic, viable HVJ-pi-injected tumor cells as an immunogen for inducing tumor immunity.