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Evaluation of HLA matching for CREG antigens in Europe
Insights
Cross-reactive antigen group (CREG) matching for kidney transplants does not improve outcomes. Graft survival depends on HLA-A+B mismatches, not CREG grades, in European cadaver kidney allocation.
Area of Science:
- Immunogenetics
- Transplantation immunology
- Organ allocation
Background:
- Cross-reactive antigen group (CREG) matching was recently adopted in North America for cadaver kidney allocation.
- This strategy aims to enhance graft outcomes and increase transplants for patients with rare human leukocyte antigens (HLA).
Purpose of the Study:
- To evaluate the impact of CREG matching on cadaver kidney transplant outcomes in Western Europe.
- To compare CREG matching with the conventional HLA-A+B mismatching scheme.
Main Methods:
- Analysis of 59,516 first cadaver kidney transplants from the Collaborative Transplant Study data.
- Utilized 10 HLA class I CREGs for comparison against HLA-A+B mismatching.
Main Results:
- Kidney transplant outcomes are primarily determined by HLA-A+B mismatches, not CREG match grades.
- Retrospective analysis showed a correlation between CREG and HLA-A+B mismatches.
- Prospective CREG matching simulations did not demonstrate improved HLA-A+B matching benefits.
Conclusions:
- Observed positive effects of CREG matching in retrospective analyses are attributed to underlying HLA-A+B matching.
- CREG-based kidney allocation in Europe would be less effective than the current HLA-A+B+DR allocation system.
Background:
In North America, cross-reactive antigen group (CREG) matching was introduced recently for cadaver kidney allocation. This is expected to result in improved graft outcome and an increased number of transplants for patients with rare HLA antigens.
Methods:
We analyzed the impact of CREG matching using the data of the Collaborative Transplant Study for 59,516 first cadaver transplants performed in Western Europe. The 10 HLA class I CREGs described by Takemoto et al. were used for a comparison with the conventional HLA-A+B mismatching scheme.
Results:
Transplant outcome depends primarily on the number of HLA-A+B mismatches and not on the CREG match grades. In a retrospective analysis, CREG mismatches correlated with the number of HLA-A+B mismatches. However, in computer simulations, we found that prospective CREG matching is not associated with beneficial HLA-A+B matching.
Conclusion:
The positive CREG matching effect observed in retrospective analyses is caused by the underlying effects of conventional HLA-A+B matching. CREG-oriented cadaver kidney allocation in Europe would, therefore, be inferior to the current conventional HLA-A+B+DR allocation.