An ethnic role for chronic, but not acute, graft-versus-host disease after HLA-identical sibling stem cell transplantation

Among 424 HLA identical siblings undergoing stem cell transplantation, 364 were Scandinavians and 60 represented other ethnic groups. The cumulative probabilities of acute graft-versus-host disease grades II-IV were similar in both groups, 17% in Scandinavians and 12% in the others, p = 0.4. In a multivariate analysis, less effective immune suppression with cyclosporine or methotrexate alone (p = 0.001), recipient seropositive for three to four herpes viruses (p = 0.004), CMV-seropositive recipient (p = 0.05) and early engraftment (before day 15) (p = 0.05) were independent risk-factors for acute GVHD grades II-IV. The cumulative probabilities of chronic GVHD were 47% and 68% in the two ethnic populations, respectively (p = 0.004). In multivariate analysis, higher patient age (p < 0.001), non-Scandinavian population (p < 0.001) and immunised female donor to male recipient (p = 0.03) were independent risk factors for chronic GVHD. The higher incidence of chronic GVHD could not be explained by differences in HLA antigen frequencies. The cumulative probabilities of relapse were 37% in the both groups. This suggests that the Scandinavian population is more homogeneous with regard to minor histocompatibility antigens important for chronic, but not acute GVHD.