6.1
TITLE: THE ACCEPTABLE MISMATCH PROGRAM IS AN EXCELLENT TOOL TO TRANSPLANT IGHLY SENSITISED PATIENTS ON THE RENAL WAITING LIST

Ilias I Doxiadis,¹ Peter de Lange,¹ Marian Witvliet,¹ Guido G. Persijn,¹ Frans H. Claas.<sup>1

1</sup>Immunohaematology and Bloodtransfusion, Leiden University Medical Center, Leiden, Netherlands

Highly sensitised patients (HSP) are difficult to transplant and TEND TO accumulate on the waiting list. HSP have current (CUR) and/or historical (HIS) HLA alloantibodies with panel reactive antibody values (PRA) of ⩾ 85%. Within Eurotransplant, HSP are offered the possibility to enter the Acceptable Mismatch (AM) Program. The principle of this program is that a negative crossmatch (XM) is predicted on the basis of the compatibility of the donor HLA–A, B, DR antigens with the patients HLA antigens in combination the AM. AM are HLA antigens towards which the patient never has formed antibodies. HIS and CUR sensitisation is considered equally important. AM are defined by analysis of the HLA typing of panel donors with negative screening reactions, which is only possible when the PRA is less than 100%. Additional AM are defined by performing XM with blood donors with one HLA mismatch to the patient`s phenotype. In case a patient is selected via the AM Program, the exchange is mandatory. To date >550 HSP entered the program and >400 have been transplanted. 60% of the AM patients received the offer within 21 months on the AM waiting list, compared to 18% if patients are not included in a special program. Since 1995, 152 HSP were transplanted. The 2 years overall graft survival was 84%, identical to not sensitised patients. No difference in graft survival was observed between HSP with CUR or HIS sensitisation only. Matching seems not to play a role. In conclusion, introduction of the AM program has shortened waiting of HSP and results in a similar graft survival as observed in non sensitised patients.