Outcome of boost haemopoietic stem cell transplant for decreased donor chimerism or graft dysfunction in primary immunodeficiency.

ABSTRACT

Haemopoietic stem cell transplants (HSCT) cure increasing numbers of primary immunodeficiencies (PID) residual recipient T-cell function increases risk of incomplete or decreasing immune reconstitution, which may resolve following a second, unconditioned, infusion from the same donor (boost infusion). We assessed the outcome of 20 boost infusions in 19/139 patients transplanted for PID patients at our centre since 1987. Boost infusion was given 64-1226 days after the original HSCT. Follow-up was 4-124 months. In all, 12 of 19 patients cleared viral infection (6), or showed sustained increase in donor chimerism, T- and B-cell numbers and function, or other markers (6). In 7/12 patients, immunoglobulin replacement has been discontinued. Four were partially successful with stable low-level chimerism (two patients) or improved T-cell function, but not B cell function (two patients). Four failed with no change in donor chimerism or cell number. No significant association with donor source, T-cell depletion, conditioning regimen, boost infusion stem cell dose or time from original HSCT to boost was found. One patient developed grade III acute graft-versus-host disease despite cyclosporine, and one developed severe pneumonitis; both have recovered. Boost infusion was successful or partially successful in 84% of patients. The risk of adverse effects is low.