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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.

Background: The traditional method for assessing HLA antibodies in recipient serum samples is the complement-dependent cytotoxicity testing (CDC). Recently, the highly sensitive microbead-based Luminex assay was introduced and can detect low levels of anti-HLA Abs., Objective: To determine the impact of pretransplant donor-specific HLA antibodies (DSA) detectable by Luminex, despite a negative CDC crossmatch, on the outcomes of kidney transplantation. The correlation and cut-off value of panel reactive antibody (PRA) and DSA was also evaluated., Methods: Pre-transplant sera from 116 kidney transplant recipients with a negative CDC crossmatch were assessed for donor-specific HLA antibodies by using Luminex single antigen beads. The patients received kidney transplants at Ramathibodi Hospital between January 2003 and December 2007. The results were correlated with kidney graft outcomes., Results: DSA were found in 24.1% (28/116) of all recipients. Of the twenty-eight DSA positive patients, four developed antibody-mediated rejection (AMR) (4/28 = 14.3%). All these 4 patients had positive C4d staining in their biopsies. Of the eighty-eight DSA negative patients, two developed AMR (2/88 = 2.3%). The AMR occurred more frequently in the DSA positive group than in the DSA negative group (14.3% versus 2.3%. The patient and graft survival were similar in both groups. The strength of pre-transplant DSA was not associated with the incidence of rejection episodes., Conclusion: There was a higher incidence of AMR in patients with pre-transplant DSA despite a negative CDC crossmatch. However, pre-transplant DSA detected by Luminex had no statistically significant impact on delayed graft function, patient survival and graft survival.