Association of soluble human leukocyte antigen-G with acute tubular necrosis in kidney transplant recipients.

BACKGROUND: Human leukocyte antigen (HLA)-G is a nonclassical HLA class I molecule that displays strong immune-inhibitory properties and has been associated with allograft acceptance. However, there are conflicting data on the correlation of soluble HLA-G (sHLA-G) and acute rejection and no data on the correlation with acute tubular necrosis in kidney transplantation. OBJECTIVE: To evaluate the association of sHLA-G level in early post-transplant period and allograft rejection/ and acute tubular necrosis (ATN) in kidney transplant recipients. METHODS: The sera procured before transplantation and serially on day 3 and day 7 after transplantation from 76 kidney transplant recipients were analyzed for the level of sHLA-G by enzyme-linked immunosorbent assay. RESULTS: The levels of sHLA-G from three serial sera did not differ between patients with acute rejection and patients without rejection. However, the sHLA-G levels on day 3 post-transplant and day 7 post-transplant in patients with ATN were significantly higher than that in patients without ATN (16.3 vs 9.85 U/ml, p = 0.018, for day 3 post-transplant and 12.47 vs 5.42 U/ml, p = 0.044, for day 7 post-transplant). In addition, the ROC analysis of sHLA-G for identifying patients with ATN showed that the area under curve was 0.67 (95% confidence interval 0.54-0.80). CONCLUSIONS: There was no significant difference for sHLA-G levels between patients with acute rejection and without rejection. Interestingly, high levels of sHLA-G in day 3 and day 7 after transplantation were associated with acute tubular necrosis. Our findings raise the question whether the increased levels of sHLA-G in patients with acute tubular necrosis after transplantation might be a result of ischemia and reperfusion injury.