HLA‐G on peripheral blood CD4+ T lymphocytes: a potential predictor for acute renal rejection

HLA‐G Expression in grafts and serum has been shown to improve graft acceptance. However, its expression on peripheral blood lymphocytes (PBLs) during acute rejection (AR) remains unknown. In this study, we serially monitored HLA‐G expression on CD4⁺ and CD8⁺ PBLs of 66 recipients undergoing renal transplantation using flow cytometry at different time points before and after transplantation, as well as during AR episode. In stable recipients, HLA‐G expression on CD4⁺ PBLs declined during the first week after transplantation and increased continuously with immunosuppressive therapy. Then, expression declined gradually after 1 month and remained at a higher level compared with pretransplantation. When AR occurred, HLA‐G expression decreased significantly compared with the stable level. In three recipients suffering from recurrent rejection, it remained at a low level despite impact immunosuppressive treatment. With mix lymphocyte assay, HLA‐G⁺ CD4⁺ T cells showed inhibitory role on proliferation of peripheral blood mononuclear cell. HLA‐G expression on CD8⁺ PBLs was almost undetectable at different time points in the recipients and healthy controls. Our results suggest that HLA‐G on CD4⁺ PBLs might provide a potential marker for the early diagnosis of renal AR and for the immunosuppressive status of recipients.