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The influence of cytomegalovirus (CMV) infection on the HLA expression on cultured biliary epithelial cells (BEC) was investigated. CMV-infection augmented expression of HLA class I but not of HLA class II. CMV reduced the IFN-gamma-mediated induction of the de novo expression of HLA class II while the stimulated expression of HLA class I was not impaired. Autologous but not allogeneic PBL responded to CMV-infected BEC. This response resulted in upregulation of HLA class I on BEC which was significantly higher compared with the expression on infected BEC alone or on uninfected BEC cocultured with autologous PBL. The results suggest that CMV modulates the immunogenic potential of BEC, which is important for the HLA and CMV-mediated pathomechanisms in vivo.

Flow cytometric analysis and cellular assays were used to determine constitutive and induced expression of class I HLA antigens and class II antigens encoded by the HLA-DR, -DQ and -DP subregions on cultured human arterial endothelial cells (HAEC) derived from transplant donors. Class I but no or minimal quantities of class II HLA antigens were found on HAEC. Prior incubation of HAEC with gamma-IFN increased class I HLA antigen expression and induced class II HLA antigen expression on HAEC. The induced expression of HLA-DQ was lower than that of HLA-DR, but both were significantly reduced in comparison to the frequency of these antigens on EBV transformed lymphoblastoid cell lines derived from the same donor. In addition, supernatants from class I and class II alloreactive clones were shown to induce class II antigen expression on HAEC. By PLT analysis, it was shown that these antigens are functionally capable of generating a lymphocyte response. In this regard, HAEC have proved to be a helpful tool in designing in vitro lymphocyte-endothelial cell studies.