Donor CTLA-4 Genotype Modulates the Immune Response to Minor Histocompatibility Antigen Mismatches

Minor histocompatibility antigen (miHA) mismatches have been related to graft-versus-host disease (GVHD) after allogeneic stem cell transplantation, but this association remains controversial due to the lack of consistency in the results obtained by different groups. The CTLA-4 genotype of the donor has been reported to be relevant in the appearance of acute GVHD. We explored the effect of the donor's CTLA-4 genotype in the incidence of acute GVHD associated with HA-1, HA-8, or H-Y miHA mismatches in a large cohort of 1295 patients receiving an allogeneic transplant from an HLA-identical sibling donor. The incidence of acute GVHD was higher if the donor and recipient were mismatched for HA-1, HA-8, or H-Y, but only when the donor had the CTLA-4 rs231775 AA genotype (hazard ratio [HR], 2.18; 95% confidence interval [CI], 1.27 to 3.75; P=.005; HR, 2.11, 95% CI, 1.06 to 4.18; P=.033; and HR, 1.50; 95% CI, 1.05 to 2.15; P=.025, respectively). In contrast, this increased risk of developing acute GVHD was not found when the donor presented the CTLA-4 rs231775 AG or GG genotypes. We conclude that the immune response to specific miHA mismatches is modulated by the CTLA-4 genotype of the donor.
Supported in part by grants PI11/01690 and PI14/01646 from the Fondo de investigaciones sanitarias, Institute de Salud Carlos III, FEDER (Fondo Europeo de desarrollo regional), and grant MTV3/120210 from the Fundacio la Marato de TV3.