Immunogenicity of MHC class I alloantigens expressed on parenchymal cells in the human kidney.

The goal of the present study was to examine the capacity of human kidney cell lines (KCL) to elicit T cell responses to MHC class I alloantigens. KCL exhibited the phenotypic characteristics of tubular epithelial cells and were devoid of detectable contamination with leukocytes. Coculture of normal peripheral blood leukocytes (PBL) with allogeneic KCL elicited cytolytic T lymphocytes (CTL) that lysed the stimulating KCL but failed to lyse third-party KCL. Cell panel and antibody blocking studies demonstrated that the CTL were directed to the HLA class I alloantigens expressed on the KCL stimulators. Purified T cells completely failed to mount a CTL response to KCL, but the response could be reconstituted by supplementing the cultures with either autologous non-T cells or supernatant from a mixed lymphocyte culture (MLC). IL-2, but not IL-1, IL-4, IL-6, or gamma-interferon, restored the anti-KCL response, suggesting that IL-2 is the active factor in the MLC supernatant. Induction of class II antigens on the KCL stimulators with gamma-IFN failed to restore a CTL response, suggesting that KCL are deficient in a costimulatory factor important for class II restricted T helper responses. Nonetheless, our data demonstrate that parenchymal cells in the kidney are capable of presenting class I antigens to alloreactive T cells and, therefore, may contribute to the immunogenicity of renal allografts.