Successful transplantation of marrow from an HLA-A, -B, -D mismatched heterozygous sibling donor into an HLA-D-homozygous patient with aplastic anemia.

A patient with aplastic anemia who was found to be homozygous for an HLA-D determinant shared by her unrelated parents achieved sustained engraftment and full restoration of hematopoietic and lymphoid function following a transplant from an HLA-A and -B nonidentical, ABO incompatible sibling who was heterozygous for the shared HLA-D specificity. Transplantation was complicated by transient graft-versus-host disease of moderate severity, which resolved completely following treatment with antithymocyte globulin and prednisone. The case indicates that patients found to be HLA-D-homozygous may be successfully transplanted from HLA-D-heterozygous sibling donors despite HLA-A and HLA-B incompatibilities, and thus further demonstrates the importance of the HLA-D region as a marker of donor-host histocompatibility.