Fetal antigens associated with adenovirus 12 mouse tumors

The fetal antigen(s) of C3H/BfB/Ki mouse tumor cells induced by adenovirus type 12 was examined by transplantation resistance, local adoptive transfer and in vitro cell-mediated microcytotoxicity tests. Mice immunized with 8 to 9-day gestation fetal cells showed weak resistance to the challenge of small numbers of tumor cells, but immunization with 13 to 14-day gestation fetal cells did not confer transplantation immunity. Local adoptive transfer of multiparous pregnant mouse spleen cells mixed with tumor cells showed a small inhibition of tumor growth in all cases, but primiparous pregnant mouse spleen cells showed a protective effect in only one of three samples. In the cell-mediated microcytotoxicity test, spleen cells taken from the fetal tissue-immunized or multiparous pregnant mice showed a cytotoxic effect to MT-2 cells (adenovirus type 12 tumor cell line) and mouse fetal cells, but not to newborn mouse kidney cells. These results strongly suggest the presence of phase-specific tumor-associated fetal antigen(s) which can evoke transplantation immunity.