Influence of Minor Histocompatibility Antigens' Disparities On Graft Versus Host Disease and Overall Survival After Allogeneic Hematopoietic Cell Transplantation From Siblings

Minor histocompatibility antigens (MiHA) are acknowledged non-HLA genetic factors which, in case of their incompatibility between the donor and the recipient, may contribute to post-transplant complications and impact the results of transplantation. The aim of this study was to investigate whether immunogenic MiHA disparities in either Graft-versus-Host or Host-versus-Graft direction influence Graft Versus Host Disease (GVHD) and overall survival after allogeneic hematopoietic cell transplantation (allo-HCT) from matched siblings.

Alleles encoding 11 MiHAs: HA-1, HA-2, HA-3, HA-8, HB-1, ACC-1, ACC-2, HwA-9, HwA-10, UGT2B17 and HY were examined in 62 sibling donor/recipient pairs with use of Dynal AllSet mHA typing kit and PCR-SSP method. Only immunogenic MiHA disparities determined in accordance to dbMinor database, with regard to their GVH or HVG direction, were assessed. Median age of donors and recipients was 35(14–60) and 38(14–59) years, respectively. Median time from diagnosis to allo-HCT was 0.62(0.24–12.91) years. Allo-HCTs were performed between 2000–2008 for following indications: AML, ALL, MDS, CML and NHL. The conditioning treatment before allo-HCT was myeloablative (BuCy, TBI/Cy), reduced toxicity (Treo/Flu) or nonmyeloablative. Median follow-up was 3 (0.04–10) years.

Immunogenic MiHA mismatches were observed in 42 (68%) donor-recipient pairs: GVH- or HVG- directed in 18 pairs each and bidirectional in 6 pairs. Acute GVHD was observed in 27 patients, in 24 of whom it was severe (grade III or IV) and it was influenced by GVH-directed disparities of MiHA encoded by Y-chromosome (p=0.037), as shown in Fig. 1. Chronic GVHD was diagnosed in 25 patients, in 12 of them extensive, and it's incidence was influenced by the same kind of MiHA disparities (p=0.017), as shown in Fig. 2. Analysis of overall survival showed unfavorable impact of GVH-directed disparities of Y-chromosome encoded MiHAs (p=0.011), as presented in Fig. 3.

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Influence of GVH-directed mismatches of Y-chromosome encoded MiHAs on:

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Influence of GVH-directed mismatches of Y-chromosome encoded MiHAs on:

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Mismatches of Y-chromosome encoded MiHAs significantly impact the occurrence of severe acute and extensive chronic GVHD and decrease overall survival.

No relevant conflicts of interest to declare.