A fully major histocompatilbility complex (MHC) matched donor is not available for the majority of patients in need of a haematopoietic stem cell transplantation (SCT), which illustrates the need for a tool to define acceptable MHC disparities. Previously, we noticed that a variety of single MHC class I mismatched allogeneic donor-recipient pairs did not elicit an allogeneic cytotoxic-lymphocyte (CTL) response in vitro if the MHC amino-acid sequences had five or more differences in the α-helices plus five or more differences in the β-sheet (≥α5β) (7). To address the clinical relevance of this observation, we analysed CTL precursor (CTLp) assay outcome and SCT outcome in 53 Dutch recipients of a single MHC class I mismatched graft from an unrelated donor. Overall patient survival was 44% after 4 years. In multivariate analysis, recipients of a ≥5α5β mismatched graft with negative CTLp frequencies in vitro before transplantation demonstrated superior survival: survival at 4 years was 80% as compared to 47% in recipients of other mismatched grafts with negative CTLp frequencies (hazard ratio = 0.131; 95% CI = (0.03-0.61); P = 0.009). This option of acceptable mismatches may enlarge the pool of potentially acceptable stem cell donors.

dx.doi.org/10.1038/sj.bmt.1705721, hdl.handle.net/1765/35925
Bone Marrow Transplantation
Erasmus MC: University Medical Center Rotterdam

Heemskerk, M.B.A, Cornelissen, J.J, Roelen, D.L, van Rood, J.J, Claas, F.H.J, Doxiadis, I.I.N, & Oudshoorn, M. (2007). Highly diverged MHC class I mismatches are acceptable for haematopoietic stem cell transplantation. Bone Marrow Transplantation, 40(3), 193–200. doi:10.1038/sj.bmt.1705721