To investigate the association between pre-transplantation endomucin (EMCN) antibodies and antibody-mediated rejection (ABMR) and graft prognosis.

Patients diagnosed with ABMR by renal allograft biopsy in the Shangxi Second People′s Hospital from 2021 to 2022 were selected as the case group (n=18), and recipients who underwent renal transplantation in 2022 and had stable renal allograft function were selected as the control group (n=37). Another 9 recipients were diagnosed as non-ABMR by renal allograft biopsy and included in the graft prognosis analysis. The differences of EMCN antibodies before transplantation between the two groups were compared, the optimal cutoff value of EMCN antibodies before transplantation was determined using receiver operating characteristic (ROC) curves. The effect of EMCN antibodies before transplantation on renal allograft survival and functional deterioration was analyzed, and the risk factors for the occurrence of ABMR were analyzed by univariate and multivariate Cox proportional hazards models.

The corrected values of EMCN antibody before transplantation were (0.87±0.64) and (0.41±0.31) in the case group and the control group, respectively, and the difference was statistically significant (t=2.85, P<0.05). Pre-transplant EMCN antibody levels were predictive of ABMR development, with an area under the ROC curve of 0.7679 (95%CI 0.64-0.90, P<0.05). The cutoff value was determined to be 0.4276, with a sensitivity of 70.59% and a specificity of 70.27%. There was no significant difference in the survival rate of transplanted kidneys between EMCN-positive recipients and EMCN-negative recipients before transplantation (P>0.05). The proportion of EMCN-positive recipients with confirmed or highly suspected ABMR by renal allograft biopsy was higher than that of EMCN-negative recipients (41.4% and 14.3%), and the proportion of deteriorated renal allograft function was also higher than that of EMCN-negative recipients (48.3% and 11.4%) (P<0.05). EMCN antibody and HLA-DSA before renal transplantation were independent risk factors for ABMR after surgery (HR = 5.50 and 5.56, 95%CI 1.89-16.06 and 1.08-28.63), and the shorter the cold ischemia time of the donor kidney, the lower the risk of ABMR (HR=0.41, 95%CI 0.25-0.70).

Pre-transplantation EMCN antibody is associated with ABMR and graft function deterioration after renal transplantation, and has a predictive effect on ABMR, and is an independent risk factor for the ABMR.