Update HLA Equivalency Tables, 2023
At a glance
Histocompatibility laboratories test compatibility of transplant candidate and organ donor tissues using the human leukocyte antigen (HLA) system. This process is also known as HLA typing. When a candidate is more compatible with the donor, there is less risk the candidate’s body will reject the transplant.
The laboratories use commercially available kits to do the tests. The antigens used in the testing are included in tables in OPTN policy and programmed into the OPTN computer system known as UNetSM.
During their 2023 annual review, the OPTN Histocompatibility Committee identified three changes that should be made to the reference tables of HLA tables within OPTN policy and programmed into the OPTN computer system:
- Add specific HLA known as P-groups to HLA typings
- Update HLA matching equivalences to that higher resolution donor typings will match with all candidates within the same serologic antigen group
- Update the HLA DPB1 tables to remain current
- What it's expected to do
- Better ensure safety, equity, and accuracy in matching donors with transplant candidates
Terms to know
- Alleles: Variations of a gene that can result in different traits in individuals. An individual inherits two alleles for each gene, one from each parent.
- Calculated Panel Reactive Antibody (CPRA): An algorithm used to determine what proportion of deceased donors a potential candidate may be unable to accept organs from due to immunologic incompatibility.
- Histocompatibility: The examination of HLA in a patient, often referred to as "tissue typing" or "genetic matching”; tissue typing is routinely performed for all donors and transplant candidates to help match the donor with the most suitable recipients to help decrease the likelihood of rejecting the transplanted organ.
- Human leukocyte antigen (HLA) system: A group of proteins that help the immune system distinguish the body's own cells from foreign invaders
- UNetSM: The OPTN computer system used to house all donor information, transplant patient information, and data reports needed to evaluate the nation’s organ donation and transplant system
Read the full proposal (PDF)
Region 8 | 09/19/2023
Sentiment: 8 strongly support, 7 support, 3 neutral/abstain, 0 oppose, 0 strongly oppose
This was not discussed during the meeting, but attendees were able to submit comments with their sentiment. The region supports the updated tables and noted the addition of the P-groups was especially helpful.
Association of Organ Procurements Organizations | 09/19/2023
AOPO strongly supports updates to HLA equivalency tables proposed by the OPTN during the summer comment period. The OPTN’s recent incorporation of P groups for HLA-DPB1 provided much needed clarification but did not account for the remaining HLA loci. Incorporation of P groups without addressing the remaining HLA loci has led to “discrepant typings” of lab results when, for example, an OPO lab types using a low-resolution method and the receiving transplant center uses a high-resolution method, such as Next-Generation Sequencing (NGS).
OPO Lab Directors are HLA subject matter experts and understand that “discrepancies” can occur when an OPO lab, using low-resolution testing, reports the presence of an unacceptable DPB1-Locus antigen, like DPB1*03:01P, and the transplant center, using high-resolution testing, obtains an HLA value of DPB1*104:01 which has no equivalent DPB1-Locus antigen in the current equivalency table because only the DPB1*03:01 antigen is listed. Because the HLA equivalency table does not currently include the DPB1*03:01P antigen, this situation would cause the transplant centers to view the OPO laboratory result as erroneous even though there is no discrepancy because the P group is shared. The shared P group is not specified in the current HLA-DPB1 equivalency table because only the DPB1*03:01antigen is included in the table and not DPB1*03:01P antigen.
This “discrepancy” does not present an actual risk to patient safety because DPB1*03:01P and DPB1*104:01 are both considered equivalent to the unacceptable DPB1*03:01 antigen. However, the UNOS Patient Safety flagging system recognizes these differing results as posing an unacceptable risk to patients. When these “discrepant” results are flagged, very busy lab directors are required to “resolve discrepancies” that do not actually exist by initiating an investigation into the “discrepancy” and communicating the results of the investigation and a lengthy explanation of the issue to the OPTN’s Membership and Professional Standards Committee. Updates to the equivalency table will reduce the necessity for needless administrative exercises and permit OPO laboratories to focus on their lifesaving missions.
Further, as HLA typing methodologies continue to advance and future technologies are developed to provide two-field high-resolution in the same time frame as laboratories currently perform donor HLA typing, equivalency tables updates will become even more critical. Proactively supporting the proposed update to the HLA equivalency tables is a positive step toward supporting novel and developing technologies now, rather than trying to play catch up in the future.
Region 9 | 09/19/2023
Sentiment: 5 strongly support, 5 support, 3 neutral/abstain, 0 oppose, 0 strongly oppose
Region 3 | 09/19/2023
Sentiment: 2 strongly support, 10 support, 4 neutral/abstain, 0 oppose, 0 strongly oppose
Region 10 | 09/19/2023
Sentiment: 4 strongly support, 8 support, 4 neutral/abstain, 0 oppose, 0 strongly oppose
This was not discussed during the meeting, but attendees were able to submit comments with their sentiment. An attendee stated that this update is needed in order to alleviate waitlist issues in the current process and decrease required communication of OPO HLA representatives with transplant program HLA representatives.
UC San Diego Health | 09/19/2023
The UC San Diego Health Center for Transplantation appreciates the Histocompatibility Committee’s ongoing efforts to better ensure safety, equity, and accuracy in matching donors with transplant candidates. The importance of keeping the reference tables within OPTN policy and programmed into the OPTN computer system up to date with clinical practice cannot be overstated.
OPTN Kidney Transplantation Committee | 09/18/2023
The OPTN Kidney Committee thanks the OPTN Histocompatibility Committee for the opportunity to provide a public comment on the proposal. The Committee supports the proposal as it will improve and impact long-term outcomes, thereby decreasing the need for repeat transplants, making more organs available for initial transplants.
Region 7 | 09/18/2023
Sentiment: 1 strongly support, 9 support, 5 neutral/abstain, 0 oppose, 0 strongly oppose
Region 1 | 09/15/2023
Sentiment: 0 strongly support, 2 support, 3 neutral/abstain, 0 oppose, 0 strongly oppose
Gift of Life Michigan | 09/15/2023
We appreciate the Histocompatibility Committee's work to update these equivalency tables, and strongly support their adoption.
Region 6 | 09/15/2023
Sentiment: 3 strongly support, 9 support, 0 neutral/abstain, 0 oppose, 0 strongly oppose
American Society of Transplantation | 09/15/2023
The American Society of Transplantation (AST) supports the proposal, “Update Human Leukocyte Antigen (HLA) Equivalency Tables, 2023.”
American Society for Histocompatibility and Immunogenetics | 09/14/2023
The American Society for Histocompatibility (ASHI) and its National Clinical Affairs Committee (NCAC) appreciate the opportunity to provide feedback around the update to the HLA Equivalency tables. ASHI agrees with these updates. Additionally, ASHI and NCAC recommend removing older nomenclature such as B5, B17, DR5, DR6, etc. to reduce confusion when reporting HLA antigens. With the increased use of molecular typing, a complete revamp of these tables would be useful.
Region 5 | 09/13/2023
Sentiment: 6 strongly support, 16 support, 0 neutral/abstain, 0 oppose, 0 strongly oppose
An attendee inquired about the rationale in Table 4-2, whether there was concern this will create confusion; for example, one can select both A*01:01 or A*01:01P—why not just use the P group. A*32:04 is listed as matched equivalent to A3. Yet, this allele bears sequences (eplets 76ESI, 81ALR) not present in A3 but present in other A32 and A25, etc.
Region 11 | 09/12/2023
Sentiment: 5 strongly support, 6 support, 2 neutral/abstain, 0 oppose, 0 strongly oppose
Michael Gautreaux | 09/12/2023
I support this change.
American Nephrology Nurses Association (ANNA) | 09/11/2023
ANNA supports this update and agree that changes should reflect current practices.
Region 2 | 09/01/2023
Sentiment: 8 strongly support, 7 support, 5 neutral/abstain, 0 oppose, 0 strongly oppose
This was not discussed during the meeting, but attendees were able to submit comments with their sentiment. It was noted that this update is needed for high resolution results.
Region 4 | 08/30/2023
Sentiment: 8 strongly support, 11 support, 2 neutral/abstain, 0 oppose, 0 strongly oppose
This was not discussed during the meeting, but attendees were able to submit comments with their sentiment. One attendee commented that this update is a good step forward but was concerned that the high-resolution list is incomplete. They added that some alleles don't exist in the proposed table and are only identified at low resolution or serology. They went on to comment that using the International ImMunoGeneTics (IMGT) for the nomenclature/coding would have been strongly preferred. They were also concerned about the use of P groups as these are only a part of protein and although they predict T cell immunity, they are a poor proxy for antibody reactivity. Another attendee commented that the updates will enhance compatibility opportunities.