HLA matching in the new millennium

Area of Science:

• Transplantation immunology
• Histocompatibility

Background:

• Despite advances in immunosuppression, human leukocyte antigen (HLA) mismatches increase kidney transplant graft loss risk by ~25% compared to zero mismatches.
• The proportion of zero HLA-DR-mismatched transplants has declined since 1994, while the use of flow crossmatch has increased significantly.

Purpose of the Study:

• To analyze trends in HLA matching and crossmatch techniques in kidney transplantation.
• To evaluate the impact of HLA matching and crossmatch methods on graft survival.
• To present and assess novel HLA matching models using Cell Release Engineering Groups (CREGs).

Main Methods:

• Analysis of historical transplant data from 1988 to 2003.
• Comparison of graft loss risk between HLA-mismatched and zero-mismatched transplants.
• Development and evaluation of HLA matching models incorporating 9, 18, and 36 CREGs.

Main Results:

• A higher relative risk of graft loss persists for transplants with HLA mismatches.
• Flow crossmatch use increased substantially, with a notable shift in its association with graft loss risk around 1995.
• Significant differences in HLA antigen distributions exist between White and Black populations.
• More complex HLA matching models (e.g., 36 CREGs) reduced the number of transplantable cases but improved outcomes, nearing those of zero ABDR-mismatched transplants.

Conclusions:

• HLA matching remains a crucial factor influencing kidney transplant outcomes.
• Evolving crossmatch protocols require careful evaluation regarding their impact on graft survival.
• Advanced HLA matching strategies, particularly those using CREGs, offer potential for optimizing transplant success.