Expression of alien minor histocompatibility antigens distinct from tumor‐specific transplantation antigen on a murine fibrosarcoma

Abstract

The fibrosarcoma ST2, induced by 3-methylcholanthrene in BALB/c (H-2d) mice, also expressed alien histocompatibility antigens of the C3Hf and B10 background not encoded by the MHC. To examine the relationship between these alien, minor antigens and the tumor-specific transplantation antigen (TSTA) of the tumor, in vivo immunogenicity test were performed in BALB/c mice and in hybrids between BALB/c and C3Hf (H-2k), C3H.OH (H-2o2), C3H.SW (H-2b), BALB.K (H-2k), B10.BR (H-2k), and B10.D2 (H-2d) mice. A significant loss of TSTA immunogenicity was found in (BALB/c x C3Hf) and in (BALB/c x C3H.OH)F1 animals and, to a lesser extent, in (BALB/c x C3H.SW)F1 mice as compared to the immunogenicity of the tumor in BALB/c mice. Immunogenicity tests with ST2 in BALB/c x (BALB/c x C3Hf) or in BALB/c x (BALB/c x B10.D2) backcross mice, respectively, revealed that half of the BALB/c x (BALB/c x C3Hf) and 97% of the BALB/c x (BALB/c x B10.D2) animals were able to mount an immune response to ST2. To see whether the loss of TSTA immunogenicity in (BALB/c x C3Hf) was due to common determinants shared between TSTA and alien non-H-2 C3Hf antigens or to a genetically linked low responsiveness to TSTA introduced by C3Hf and C3H.OH strains, BALB/c mice were immunized with normal tissues of some BALB/c x (BALB/c x C3Hf) backcross, anti-ST2 resistant mice. Normal tissues of anti-ST2 resistant, dd and dk typed backcrosses were able to immunize BALB/c mice against a challenge of an otherwise lethal dose of ST2 cells. Some but not all BALB/c x (BALB/c x B10.D2) anti-ST2 resistant donors had tissues able to immunize BALB/c hosts aginst the ST2 growth. Since resistance to tumor growth and expression of minor "alien" antigens shared with the tumor segregate independently, we concluded that alien, minor C3Hf and B10 antigens of the BALB/c sarcoma ST2 are distinct from the TSTA of this tumor.