“…Residual graft versus host disease and, most importantly, delay to immune function development account for the majority of deaths. New T-cell development requires a 3-4 month minimal period, and sometimes more, to occur (1)(2)(3)(4)(5). In addition, in a minority of patients, T-cell functions remain partially defective in the long term, while in the majority B-cell function does not develop (1,2), necessitating intravenous (IV) immunoglobulin substitution for life.…”