Transplant International REVIEW The long and winding road towards epitope matching in clinical transplantation Cynthia S.M. Kramer1, Moshe Israeli2, Arend Mulder1, Ilias I.N. Doxiadis3, Geert W. Haasnoot1, Sebastiaan Heidt1 & Frans H.J. Claas1 1 Department of SUMMARY Immunohaematology and Blood Recent data suggest that HLA epitope matching is beneficial for the pre- Transfusion, Leiden University vention of de novo donor specific antibody (DSA) formation after trans- Medical Center, Leiden, the plantation. In this review, different approaches to predict the Netherlands immunogenicity of an HLA mismatch will be discussed. The parameters 2 Tissue Typing Laboratory, Rabin Medical Center, Petach-Tikva, Israel used in these models are often called epitopes but the actual antibody epi- 3 Institut fur€ Transfusionsmedizin, tope is far more complex. Exact knowledge of the antibody epitope is cru- Universitatsklinikum€ Leipzig, Leipzig, cial if epitope matching is also used as a tool to select compatible donors Germany for (highly) sensitized patients. Evidence is provided that it is not always possible to give an exact definition of an antibody epitope. We conclude Correspondence that HLA “epitope” matching is superior over HLA antigen matching with Frans H.J. Claas, Department of respect to the prevention of de novo DSA formation and will enhance the Immunohematology and Blood prediction of acceptable HLA mismatches for sensitized patients. However, transfusion, Leiden University Medical epitope matching at our current level of knowledge will not solve all histo- Center, Albinusdreef 2, 2333 ZA compatibility problems as unexpected antibody reactivity still may occur. Leiden, The Netherlands. Tel.: +31 71 5263802; Fax: +31 71 5265267; Transplant International 2019; 32: 16–24 e-mail:
[email protected] Key words antibodies, epitopes, HLA matching, immunogenicity, virtual crossmatch Received: 13 March 2018; Revision requested: 16 April 2018; Accepted: 10 October 2018; Published online: 26 November 2018 the enormous polymorphism of the HLA system.