Allograft infiltrating cytotoxic T lymphocytes recognize kidney-specific human minor histocompatibility antigens

The role of minor histocompatibility antigens (mH) in allograft immunity has been proposed, but the nature of these antigens and their immunogenicity are not well understood. We have shown that tissue-specific cytolytic T lymphocytes (CTL) can be isolated form graft infiltrating lymphocyte (GIL) populations from renal transplant recipients undergoing acute cellular rejection. In most cases these CTL were allorestricted recognizing donor mismatched kidney MHC class I antigens. In contrast, one patient's GIL T cells demonstrated specific lytic activity against HLA-B35 expressed on primary kidney epithelial cell lines (KCL) but not on B-lymphoblastoid cell lines (LCL). Since HLA-B35 was a shared antigen between donor and recipient, these results suggest that CTL within the GIL population are recognizing a tissue-specific minor histocompatibility antigen presented in the context of self-HLA-B35.