From the Guidelines
Testing organ donor compatibility involves several key steps, including ABO blood typing, human leukocyte antigen (HLA) typing, and crossmatch testing, with HLA typing examining tissue markers on cells to determine how closely the donor and recipient tissues match, as recommended by the most recent study 1. The process for testing Human Leukocyte Antigen (HLA) compatibility in organ donors is crucial for successful transplantation.
- HLA typing should be performed for major histocompatibility complex (MHC) Class I (A, B, C) and Class II (DP, DQ, DR) in donor candidates and their intended recipients, as stated in the study 1.
- Donor-specific anti-HLA antibodies should be assessed in intended recipients, as mentioned in the study 1.
- The study 1 highlights the importance of HLA-DQ typing in kidney transplantation and recommends that HLA laboratories be required to HLA type and enter both DQa and DQb allele typing information for donor and recipient.
- The degree of matching required varies by organ type, with kidney transplants benefiting from close HLA matching, while liver transplants can tolerate more mismatches, as noted in the example answer.
- Additional compatibility factors include physical matching (organ size and condition), viral status screening for infections like cytomegalovirus and Epstein-Barr virus, and assessment of recipient sensitization from previous transplants, blood transfusions, or pregnancies, as mentioned in the example answer.
- The compatibility testing process typically takes several days to complete and must be performed by specialized transplant laboratories, as stated in the example answer.
- The most recent study 1 recommends that transplant agencies prioritize collection of large patient cohorts with high-resolution HLA typing, including HLA-DQ typing, to provide the basis for further analysis and to improve transplant outcomes.
From the Research
HLA Compatibility Testing Process
The process for testing Human Leukocyte Antigen (HLA) compatibility in organ donors involves several steps, including:
- HLA typing: This is essential for solid organ and bone marrow transplantation, as well as in non-transplant settings such as disease association and pharmacogenomics 2
- Crossmatch testing: This determines the immunologic risk of a recipient with a potential donor by ensuring that there are no transplant-relevant circulating antibodies in the recipient directed against donor antigens 3
- Virtual crossmatch (VXM) testing: This assesses immunologic compatibility between recipient and potential donor by analyzing the results of two independently done physical laboratory tests - patient anti-HLA antibody and donor HLA typing 3
- Lymphocyte crossmatch testing: This is used to evaluate the compatibility of cord blood units with patients who have anti-HLA antibodies other than those against HLA-A, -B, -C, and DRB1 4
Methods of HLA Typing
There are several methods of HLA typing, including:
- Molecular methods: These include genomic profiling, next-generation sequencing, and artificial intelligence, which have improved HLA typing precision and resulted in better patient outcomes 5
- Serological methods: These include complement-dependent cytotoxicity (CDC) and flow cytometry, which are used to detect anti-HLA antibodies and determine HLA compatibility 6, 5
Importance of HLA Compatibility
HLA compatibility is crucial in solid organ transplantation, as it reduces the risk of graft rejection and improves patient outcomes 3, 5. The presence of anti-HLA antibodies can negatively impact engraftment, nonrelapse mortality, and overall survival in cord blood transplantation 4. Therefore, accurate HLA typing and crossmatch testing are essential to ensure the best possible match between donor and recipient.