Implication of HLA mismatch in the clinical outcome of orthotopic heart transplantation

Acute cellular rejection and HLA mismatch in heart transplantation: insights from a developing country

The notable evolution of heart transplant (HTX) has paralleled the capacity of diagnosing rejection and, consequently, initiating timely treatment. Acute cellular rejection, diagnosed by endomyocardial biopsy, is the most frequent in the first 6 months after HTX. HLA matching is not routinely performed in HTX due to the absence of consensus regarding its usefulness. However, the use of HLA typing might be underscored if it could predict an increased risk of rejection. Therefore, the aim of this study was to evaluate, at a public cardiology center in Brazil, the association between HLA mismatches and the incidence of acute cellular rejection in the first 6 months after HTX. Data were obtained from hospital records and from the National Transplant System. Overall, there was no association between the number of HLA mismatches and the frequency of acute cellular rejection, but there was a tendency toward a higher incidence of rejection with HLA-DR incompatibility.

Analysis of the Influence of HLA-A Matching Relative to HLA-B and -DR Matching on Heart Transplant Outcomes

Background

There are conflicting reports on the effect of donor-recipient HLA matching on outcomes in heart transplantation. The objective of this study was to investigate the effects of HLA-A matching relative to HLA-B and -DR matching on long-term survival in heart transplantation.

Methods

A total of 25 583 patients transplanted between 1988 and 2011 were identified from the International Society for Heart and Lung Transplantation registry. Transplants were divided into 2 donor-recipient matching groups: HLA-A–compatible (no HLA-A mismatches) and HLA-A–incompatible (1-2 HLA-A mismatches). Primary outcome was all-cause mortality. Secondary outcomes were graft failure-, cardiovascular-, infection-, or malignancy-related deaths.

Results

The risk of all-cause mortality 15 years after transplantation was higher for HLA-A–compatible (vs HLA-A–incompatible) grafts in patients who had HLA-B–, HLA-DR–, or HLA-B,DR–incompatible grafts (P = 0.027, P = 0.007, and P = 0.002, respectively) but not in HLA-B– and/or HLA-DR–compatible grafts. This was confirmed in multivariable Cox regression analysis where HLA-A compatibility (vs HLA-A incompatibility) was associated with higher mortality in transplants incompatible for HLA-DR or HLA-B and -DR (hazard ratio [HR], 1.59; 95% confidence interval [95% CI], 1.11-2.28; P = 0.012 and HR, 1.69; 95% CI, 1.17-2.43; P = 0.005, respectively). In multivariable analysis, the largest compromise in survival for HLA-A compatibility (vs HLA-incompatibility) was for chronic rejection in HLA-B– and -DR–incompatible grafts (HR, 1.91; 95% CI, 1.22-3.01; P = 0.005).

Conclusions

Decreased long-term survival in heart transplantation was associated with HLA-A compatibility in HLA-B,DR–incompatible grafts.

The influence of human leukocyte antigen matching on outcomes in pediatric heart transplantation

Previous adult heart transplantation studies have demonstrated that donor-recipient human leukocyte antigen (HLA) matching results in reduced graft failure and improved patient survival. No study has examined these effects in children. This study investigated the effect of HLA matching on outcomes in pediatric heart transplantation. All pediatric heart transplantation data for patients 0-18 years of age available from the United Network for Organ Sharing Transplant Registry from 1987 to 2009 were analyzed retrospectively. Donor-recipient HLA matching at loci A, B, and DR (0-6) was compared with graft survival and recipient survival. For this study, 3,751 pediatric cardiac transplantation events with complete HLA matching data were identified and grouped as having 0 to 2 matches (3,416 events) or 3 to 6 matches (335 events). The 3- to 6-match group had less graft failure than the 0- to 2-match group (28.7% vs 34.4%; p = 0.035) and greater patient survival by 5 years (81% vs 72%; p = 0.045) and 10 years (66% vs 55%; p = 0.005) after transplantation. The HLA-DR matching alone resulted in less graft failure (p = 0.038) and improved patient survival (p = 0.017). A higher degree of HLA matching in pediatric heart transplantation is associated with decreased graft failure and improved patient survival. In this study, decreased graft failure rates and superior survival also were seen with DR matching alone.

Human leukocyte antigen matching in heart transplantation: systematic review and meta-analysis

Allocation of donors with regard to human leukocyte antigen (HLA) is controversial in heart transplantation. This paper is a systematic review and meta-analysis of the available evidence. PubMed, Embase, and the Cochrane Library were searched systematically for studies that addressed the effects of HLA matching on outcome after heart transplantation. Fifty-seven studies met the eligibility criteria. 34 studies had graft rejection as outcome, with 26 of the studies reporting a significant reduction in graft rejection with increasing degree of HLA matching. Thirteen of 18 articles that reported on graft failure found that it decreased significantly with increasing HLA match. Two multicenter studies and nine single-center studies provided sufficient data to provide summary estimates at 12 months. Pooled comparisons showed that graft survival increased with fewer HLA-DR mismatches [0-1 vs. 2 mismatches: risk ratio (RR) = 1.09 (95% confidence interval (CI): 1.01-1.19; P = 0.04)]. Having fewer HLA-DR mismatches (0-1 vs. 2) reduced the incidence of acute rejection [(RR = 0.81 (0.66-0.99; P = 0.04)]. Despite the considerable heterogeneity between studies, the short observation time, and older data, HLA matching improves graft survival in heart transplantation. Prospective HLA-DR matching is clinically feasible and should be considered as a major selection criterion.