Alien histocompatibility determinants on the cell surface of sarcomas induced by methylcholanthrene. I. In vivo studies.

Groups of BALB/c mice were immunized to normal tissues (skin and/or liver plus kidney) of C3Hf, C57Bl/6, DBA/2 and AKR strains and challenged with either of two syngeneic 3-methylcholanthrene-induced immunogenic sarcomas, ST2 and TZ15, or with a "spontaneous" non-immunogenic BALB/c sarcoma, B2. It was found that anti-C3Hf and anti-DBA/2 immune mice were significantly protected against the growth of ST2, whereas anti-AKR immune mice rejected TZ15; no protection was elicited by immunizing with normal tissues of any strain against B2, which lacked individual tumor-associated transplantation antigens (TATA). The reciprocal experiment, i.e. the immunization of BALB/c mice with tumor cells and challenge with skin grafts of different strains, was also carried out with ST2 and TZ15. Accelerated rejection of all the various allogeneic skins was observed in anti-ST2 immune mice and of AKR and C3Hf skin in anti-TZ15 immune animals. In addition the Winn test demonstrated that lymph-node cells of BALB/c mice immune to C3Hf or DBA/2 tissues were specifically inhibitory for ST2, and that lymph-node cells immune to AKR tissues protected against TZ15. In a further experiment both ST2 and TZ15 tumors were left to grow in (C3Hf X BALB/c)F1, (C57Bl/6 X BALB/c)F1, (BALB/c X DBA/2)F1 and (BALB/c X AKR)F1 mice; the tumors were then excised and the "immune" mice challenged with the related tumor to measure their immune response in comparison with that elicited by the same procedure in BALB/c mice. ST2 was highly immunogenic in syngeneic BALB/c mice and in all the hybrid combinations except (C3Hf X BALB/c)F1 mice, where it completely lost its immunogenicity; TZ15 showed a certain loss of immunogenic strength in (BALB/c X AKR)F1 hybrids. It was concluded that TATA of ST2 contain antigenic determinants expressed on the normal cells of C3Hf and DBA/2 strains, and that TATA of TZ15 are likely to share antigens with AKR normal tissues.