Successful haploidentical PBSCT with subsequent T-cell addbacks in a boy with HyperIgM syndrome presenting as severe...

HIGM syndrome is a group of primary immunodeficiency disorders characterized by recurrent bacterial and opportunistic infections; it is also associated with normal to elevated serum IgM levels and a concomitant deficiency of IgG, IgA, and IgE. In this report, we give account of a boy with X-linked HIGM and a novel Y172C mutation within his CD40LG gene. He presented with severe neutropenia as the dominating symptom. His bone marrow showed maturation arrest at the promyelocyte/myelocyte stage, typical of congenital neutropenia. This boy suffered from life-threatening infections and required high doses of rhG-CSF, and a haploidentical PBSCT was also successfully performed, thus leading to reconstitution of CD40L expression on activated CD4+ T cells (as assessed with flow cytometry six months after the procedure). Two low-dose T-cell addbacks were required to re-establish full donor chimerism and clear CMV reactivation. The report demonstrates that in select cases, alternative donor allogeneic HSCT supported by DLI may be effective in correcting the defect in X-linked HIGM, and HSCT in HIGM children is not necessarily limited to matched sibling donor transplantation.