Tumor-Associated Antigens in H-2 Hemizygous Isoantigenic Variants of a Somatic Cell Hybrid, Derived From the Fusion of a 3-Methylcholanthrene-lnduced Sarcoma and a Mammary Carcinoma

Abstract

To check the suggestion that 3-methylcholanthrene-induced, sarcoma-associated, tumor-specific transplantation antigens (TSTA) could be modified H-2 antigens, reciprocal isoantigenic variants derived from TA3Ha/MSWBS hybrid cells were examined. This hybrid was produced by the fusion of the TA3Ha ascites carcinoma (H-2^a) and the 3-methylcholanthrene-induced MSWBS ascites sarcoma (H-2^S). MSWBS expresses a strong TSTA capable of inducing a rejection reaction in the syngeneic A.SW host. The genetic determinants of the H-2 complex are known to be localized on chromosome No. 17. TA3Ha contributes two normal, telocentric chromosomes No. 17 to the hybrid. In contrast, both chromosomes No. 17 of MSWBS are localized on readily identifiable translocations (17/1 and 17/M1). We have previously shown that the chromosomes No. 17 of one parental strain or the other (but not both) can be eliminated from the hybrid upon selective passage in the opposite parental strain. The present studies showed that the two strain A-compatible variants that have lost the sarcoma-derived 17-chromosomes still contained the same TSTA as the two reciprocal strain A.SW-compatible variants that have lost the mammary carcinoma-derived H-2 chromosomes. These findings argue against the possibility that methylcholanthrene-induced TST A is a modified form of H-2 or that its structural determinant(s) is localized on chromosome 17.