Soluble human leukocyte antigen-G (SHLA-G) in Tunisian kidney transplantation

To investigate the relationship between the soluble HLA-G (sHLA-G) and the appearance of acute renal rejection (AR) episodes we have quantify in this study the level of sHLA-G by enzyme-linked immunosotrbent assay in 42 kidney transplant patients classified in two groups: G1: 17patients with acute rejection (AR+) and G2: 25 patients without AR (AR-). To establish our normal sHLA-G ranges, serum samples from 18 healthy controls were tested. Pre-transplantation sHLA-G levels were significantly increased in patients (mean +/- standard error of the mean, 60.48 +/- 12.18 units/ml) than healthy subjects (19.11 +/- 4.9 units/ml) (p = 0.001). Although the difference was not statistically significant, G1 patients (AR+) revealed lower levels of sHLA-G (mean +/- standard error of the mean, 31.25 +/- 6.71 units/ml) compared to G2 patients (AR-) (53.43 +/- 1721 units/ml). Nevertheless, the course of total sHLA-G levels was nearly identical in patients with and without rejection. Nonparametric analysis revealed that pre-transplantation levels of sHLA-G < 18.00 units/ ml (sensitivity: 87.8% and specificity of 72.2%) were not related to rejection. Also, multivariate analysis regarding anti-HLA antibody status, recipient age and gender showed that sHLA-G could not be an independent risk factor for renal graft rejection. However, a higher sera levels of sHLA-G seemed to contribute to better kidney allograft survival rate after 10 years of follow-up (significance tendency: p = 0.091) as shown by the survival analysis. Because of the small number of subjects studied, these results must be treated with caution. A much larger cohort of kidney transplant patients according to acute rejection would seem necessary to confirm these findings.