A prospective study evaluating the role of donor-specific anti-endothelial crossmatch (XM-ONE assay) in predicting living donor kidney transplant outcome.

Anti-endothelial cell antibodies (AECAs) may play a role in allograft rejection. We prospectively tested 150 consecutive living donor kidney transplant recipients, with transplants performed at Northwestern Memorial Hospital between January and December 2010, using the donor-specific endothelial (XM-ONE) crossmatch. 88/150 Patients received standard of care (SOC) immunosuppression and analyzed separately, in addition to the complete study cohort. Patients were followed for one year and XM-ONE results were analyzed in relation to occurrence of acute rejection, proteinuria, serum creatinine levels, and biopsy proven fibrosis. No correlation was found between XM-ONE results and protocol or "for-cause" biopsy proven acute rejection or vasculopathy at 12 months. When IgG+ and IgM+ results of the XM-ONE assay were combined, a correlation with proteinuria at 12 months was observed (p=0.047). Although IgG+XM-ONE results were associated with significantly higher creatinine at 6 months (p=0.018), significance was lost at 12 months. Conversely, patients with an IgM+XM-ONE crossmatch had significantly lower creatinine at 1 month (p=0.019), 3 months (p=0.0045), and 6 months (p=0.038) post-transplant, but lost statistical significance at 12 months (p=0.67) post-transplant. In summary, the presence of AECAs as determined by a positive XM-ONE result was not predictive of overall poorer graft outcome after one year in our center.