HLA-DP Mismatch and Graft Outcomes

HLA-DP Mismatch and Graft Outcomes

Philadelphia—The majority of human leukocyte antigen (HLA)-A, -B, -DR zero HLA mismatch transplants are mismatched for HLA-DP, according to results of a study conducted by Nissreen S. Elfadawy, MD, and colleagues. The researchers presented study results during a poster session at Kidney Week 2014 in a poster titled HLA-DP Mismatch among the Zero GLA-A, -B, and –DR mismatched Deceased Donor Kidney Transplant Population Is Associated with Higher Risk of Both Graft Rejection and Death Censored Graft Loss.

Zero HLA mismatch results in improved graft outcomes following kidney transplantation. The United Network for Organ Sharing defines zero HLA mismatch as the absence of HLA-serologic level mismatches at HLA-A, B, and DR antigens. However, according to the researchers, it is not known whether mismatches at HLA-Cw, DQ, or DP also have an independent impact on graft outcome.

This retrospective study was designed to examine the isolated impact of mismatch on graft outcomes. The study population included 265 recipients who had shared zero mismatch deceased donor kidney transplants at the Cleveland Clinic, Ohio, from 1990 to 2012. The study population was categorized according to HLA-Cw, -DQ, -DP allele mismatch. Incidence of biopsy-proven acute graft rejection and graft loss in the different groups was determined using Kaplan-Meier plots and log-rank tests.

In this study cohort, the prevalence of HLA-Cw, -DQ, and –DP mismatch was 27%, 12%, and 77%, respectively. Following adjustment for other HLA-loci mismatches and confounding factors such as previous transplant history and degree of sensitization prior to transplantation, HLA-DP mismatches were an independent risk factor for graft rejection (12% vs 3%; hazard ratio [HR], 4.0; 95% confidence interval [CI], 1.1-26.1; P=.03), death censored graft loss (25% vs 18%; HR, 1.9; 95% CI, 1.1-3.9; P=.03), and shorter graft half life (6 years vs 8 years; P=.01).

There was no association between groups stratified by HLA-Cw or -DG mismatch with graft outcomes.

In conclusion, the researchers said, “These results suggest that the majority of HLA-A, -B, -DR zero HLA mismatch transplants are mismatched for HLA-DP. Our findings provide evidence to suggest that HLA-DP matching in renal transplant is clinically relevant and prospective typing and matching warrant further prospective investigation.”

Source: Elfadawy NS, Flechner SM, Lalli P, et al. HLA-DP mismatch among the zero HLA-A, -B, and -DR mismatched deceased donor kidney transplant population is associated with higher risk of both graft rejection and death censored graft loss. Abstract of poster presented at Kidney Week 2014, Philadelphia, Pennsylvania, November 13, 2014.