Acceptable Mismatch Program

Highly sensitised patients

Highly sensitised patients awaiting a kidney transplant are accumulating on the transplant waiting list due to their extensive list of unacceptable HLA antigens. This makes the chance of receiving a crossmatch negative donor organ through regular allocation extremely slim. Unacceptable antigens are those HLA antigens to which the patient has made antibodies that are likely to cause (hyper)acute rejection when transplanted with an organ carrying HLA antigens to which the antibodies are directed. HLA antibodies can be caused by pregnancies, blood transfusions or prior transplants.

The Acceptable Mismatch program

To facilitate transplantation of highly sensitised patients the Eurotransplant Acceptable Mismatch (AM) program was launched in 1989 for all highly sensitised patients awaiting a renal transplant within the Eurotransplant region. The goal of the program was to increase transplantation rates by predicting a negative CDC crossmatch for this patient population.

In the AM program, acceptable HLA antigens are defined pre-transplantation, which are HLA antigens to which strictly no antibodies are formed, as shown by extensive laboratory testing. The increased chance of receiving an organ is achieved by allocation based on the patient’s own HLA with the addition of acceptable antigens. Through this addition of acceptable antigens to the patient’s own HLA phenotype, in combination with mandatory shipment of a compatible organ to AM patients, increased rates of transplantation of highly sensitised patients have been achieved.

Role of the ETRL

It is extremely important to keep the AM program exclusive to those patients that are truly highly sensitised and have an extremely low chance of receiving a transplant. By using a single reference laboratory to independently check the eligibility of all patients put forward for the AM program, it is assured that only those patients truly in need of AM listing are included, and that all patients within Eurotransplant are treated equally regarding the inclusion criteria to the AM program.
Furthermore, the ETRL conducts scientific research on the outcomes of the AM program and models what possible improvements could be made to ensure maximum transplantability and the best outcomes possible.

Submission of requests for inclusion in the AM program

Before submitting a patient into the AM program, please check the following:

  • Recipients must be on dialysis for a minimum of two years.
  • Recipients must be on a transplantable status.
  • Recipients must be fully typed for HLA-A, -B, -C, -DR and -DQ both on broad and split level.

If these criteria are not met, requests are not taken into account. Submitting a request for inclusion in the AM program should be done using the following procedure:

  • Advanced notice should be sent by e-mail to the ETRL AM account.
  • Requests are submitted to the ETRL by using the AM application form accompanied by a peak serum.
  • The serum information sheet needs to be shipped together with the serum sample(s).
  • Sera and forms must preferably be shipped on Monday or Tuesday to prevent arrival at the weekend.

Upon receipt of the peak serum, the ETRL repeats the screening to confirm whether the recipient is eligible for the AM program. If the recipient fulfils criteria of the AM program, an AM form with acceptable and unacceptable antigens is sent to the tissue typing center involved. Upon returning the signed form to the ETRL, the patient will be included in the AM program. This procedure takes on average 6 weeks from the moment the serum samples have arrived at the ETRL.

For more detailed information on the AM inclusion procedure and allocation, please refer to the Eurotransplant manual chapter 10.5.3.