Biologically Unrelated Living Donor for Kidney Transplantation Associated With Higher Acute Rejection Rate but With Similar Graft Survival of a Related Living Donor

Introduction: Kidney transplantation (KT) from living donors has been shown to have multiple benefits compared to those from deceased donors. We sought to compare significant graft outcomes, namely acute rejection (AR), graft function, and survival between transplant recipients who received a kidney from living related donor (LRD) and living unrelated donor (LURD). Methods: Our cohort comprised 198 donor and recipient pairs undergoing living-donor KT at our center over 10 years. The LRD recipients were compared with LURD recipients according to demographic and clinical characteristics, transplant variables (including immunosuppression), graft function, survival, and AR rate. Results: The estimated glomerular filtration rate (eGFR) was similar in both groups over the follow-up time i.e., 60-65 mL/min (p>0.05 over 10 years). Censored graft survival was similar between LRD and LURD recipients (96.9% vs. 98.0% at five years and 87.8% vs. 79.4% at 10 years, respectively; p=0.837). The LURD recipients had a higher incidence of AR, although LURD recipient status was not an independent risk factor for AR. Multivariate analysis showed that human leukocyte antigen (HLA)-DR mismatch (MM) was an independent predictor of AR (hazard ratio (HR) 2.256, p<0.05). Both HLA-A and HLA-B MM did not affect the AR HR between the groups. Conclusion: Graft function and censored graft survival rates were similar between LURD and LRD KT recipients in our study. The AR was higher in LURD recipients, although the LURD recipient status was not an independent risk factor for AR. The HLA-DR MM was an independent predictor of AR, while HLA-A and HLA-B MM did not affect AR HR between groups of patients.