Skip to main content

Update Post-Transplant Histocompatibility Data Collection

eye iconAt a glance

Current data collection

There are three histocompatibility data collection instruments in the OPTN Computer System that are required to be completed by histocompatibility laboratories within 60 days after a transplant. These forms collect data on the donor and recipient leukocyte antigen (HLA) typings. They also collect data about recipient antibody testing, crossmatching, and HLA typing discrepancies. The Committee reviewed the data collection instruments and identified several areas for change.

Supporting media

View presentation PDF link

Proposed changes

The Committee reviewed the post-transplant histocompatibility data collection within the OPTN Computer System and identified the following areas of change:

  • Update post-transplant histocompatibility data collection forms to be consistent with current histocompatibility testing methods
  • Add data collection for virtual crossmatching to better understand its impact on patient and graft outcomes and the cold ischemic time (the time the organ spends without blood flow)
  • Create reports for all potential Human Leukocyte Antigen (HLA) critical discrepancies to increase awareness of HLA critical discrepancies and better inform future related policy updates

Anticipated impact

  • What it's expected to do
    • Align data collection with current practices
    • Collect data that will inform recipient treatment
    • Collect data that will better inform future policy updates related to critical HLA discrepancies
    • Update how the Discrepant HLA Typings Report is generated and increase the number of situations where the Discrepant HLA Typings Report will be generated for labs
  • What it won't do
    • These changes will not increase the number of data collection elements required to be submitted for the Donor and Recipient Histocompatibility Forms
    • These changes will not change any pre-transplant histocompatibility data collection

Terms to know

  • 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.
  • HLA Typing Discrepancies: Differences in the donor or recipient HLA typings between one or more labs.
  • Crossmatching: A test performed by histocompatibility laboratories used to determine the immunologic compatibility of a potential transplant recipient with a donor organ.
  • Physical crossmatching: Mixing of patient serum with donor cells to evaluate the physical immunologic reaction.
  • Virtual crossmatching: Assessment of immunologic compatibility based on candidate HLA antibody and donor HLA typing data.

Click here to search the OPTN glossary


Read the full proposal (PDF)

Provide feedback

eye iconComments

Neeraj Sinha | 01/29/2024

In the data dictionary of the histocompatibility form, how would the definition of prospective virtual crossmatch be worded? How current should the serum be for the performance of prospective virtual crossmatch?

As the immunological risk in a candidate who, for example, had a one-time historical DSA six months prior to transplant followed by repeated negative testing is different from someone who tests positive for DSA on every test before transplant; I suggest that, on page 15 of the proposal, the questions about current and historical donor specific HLA antibodies are not modified.

If the prospective virtual crossmatch was performed using a low-resolution HLA typing, and subsequently, based on high resolution donor HLA typing, it is revealed that patient did not have a DSA ('retrospective virtual crossmatch based on high resolution typing'), could this clinically relevant data be captured?


Danny Youngs | 01/24/2024

Almost all the proposed changes are good and long overdue, but I have the following concerns and suggestions.
(1) Target Source for donor HLA typing is pointless, and should not be included as a data element. It may have been questionably useful for serological typing, but it has no relevance for typing by molecular methods.
(2) For Virtual Crossmatch, is the definition of Positive, Negative and Indeterminate left up to the lab, or does the OPTN have a specific definition in mind? Some people consider the virtual crossmatch to be a prediction of the physical crossmatch, some consider it to be an evaluation of immunological risk, and some consider it be a determination of the presence/absence of donor-specific HLA antibodies. Although the three definitions greatly overlap, they are not identical. In Section III the new question "Was physical crossmatch considered concordant with virtual crossmatch?" seems to suggest that the virtual crossmatch is meant to predict the physical crossmatch. I recommend that the definition of virtual crossmatch be left up to the lab, and that the "concordant" question be eliminated. There already is an existing data element for physical crossmatch results that is not being eliminated, and any researcher mining OPTN data to establish the relationship between the virtual crossmatch and the physical crossmatch can simply do so by comparing the results for the two entries. In addition, unlike every other data element in the histo forms, the "concordant" question is not something that is likely to be easily retrievable from the lab's LIS, and would thus require onerous manual intervention and interpretation when uploading histo form data to UNet.
(3) Under Discrepant HLA Typings Report the new reason "Original Typing Confirmed Correct" makes it sound as if it applies only to the typing from the lab that first typed the donor. I suggest modifying it to something like "This Typing Confirmed Correct" so that it clearly is meant to be used for the typing from any lab, not just the original lab.