Domino donor lymphocyte infusion for secondary poor graft function after HLA‐mismatched allogeneic stem cell transplantation between HLA‐identical sibling pairs with congenital immunodeficiency

Poor graft function (PGF) is a major obstacle to successful allogeneic stem cell transplantation after achieving normal bone marrow function. We report a successful treatment of domino DLI for poor graft function in younger brother with hyper IgM syndrome from HLA-identical elder brother with the same disorder with a history of HLA-mismatched unrelated bone marrow transplantation using same donor. Immunological profiling revealed that DLI-induced T-regulatory cells could correct skewed immune responses in the BM microenvironment due to secondary PGF pathogenesis. Immunological tolerized domino DLI can be a new therapeutic option for secondary PGF in HLA-identical sibling pairs with congenital immunodeficiency.