To elucidate the mechanism of human liver allograft rejection and acceptance, T cell clones were established from liver biopsies of a liver-kidney transplant recipient during a rejection episode. Five of the clones were characterized and found to be CD4+, α/β positive T cells that proliferated specifically to the mismatched donor HLAs. Using an immunofluorescence assay, it was observed that three of these clones were recognized by autologous antibodies developed during the post-transplant period between 18 months and the end of the testing period of 36 months. Furthermore, by capping experiments, it was determined that these antibodies were recognizing the CD3-TCR complex. This was confirmed by immunoprecipitation and sequential immunoprecipitation followed by SDS-PAGE and autoradiography of lysates of radiolabeled T cell clones. Thus, our data indicate that donor-reactive T cells infiltrate into the liver allograft during rejection episodes, and that autologous antibodies reactive to the CD3-TCR complex of these cells are developed in the post-transplant period. These results support the hypothesis that the development of autoantibodies directed against or cross-reactive to the clonotypic structures of the donor-reactive lymphocytes may play an important role in the down-regulation of the immune response against the allograft.
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