Cell surface expression and alloantigenic function of a human class I MHC heavy chain gene (HLA-B7) in transgenic mice

We have introduced the gene encoding the heavy chain of the human MHC class I Ag HLA-B7 into transgenic mice. The gene was shown to be expressed at both the RNA and protein level. Cell surface HLA-B7 was detected on whole spleen cells by immunoprecipitation and on purified T cells by flow cytometry (FACS). Normal mice immunized with H-2-syngeneic B7-transgenic spleen cells generated CTL capable of killing transgenic cells and B7-expressing human JY cells. Anti-HLA mAb blocked the killing of JY cells. These results indicate that the human class I Ag HLA-B7 can be expressed at the surface of transgenic spleen cells in the absence of human β₂-microglobulin, and that a significant fraction exists in a form recognizable by nontransgenic CTL as a major histocompatibility Ag unrestricted by H-2.