Hematopoietic colony formation after allogeneic bone marrow transplantation: enhancement by cyclosporin A and anti-gamma-(immune) interferon antiserum in vitro.

Bone marrow hematopoietic progenitors (CFU-GM, CFU-E, and BFU-E) were found to be markedly decreased in 21 bone marrow transplant recipients studied from one to 51 months after transplantation. In these patients, bone marrow colony formation could be significantly enhanced by in vitro incubation of the bone marrow target with cyclosporin A (CyA; 0.5 microgram/ml) or with a monoclonal anti-gamma-(immune) interferon (IFN-gamma) antibody. Both effects were highly correlated. The data indicate that (a) endogenous elaboration of IFN-gamma may contribute to decreased colony formation in allogeneic bone marrow transplant recipients, and (b) CyA may induce a gradual release of the progenitor cell pool from IFN-gamma-mediated suppression.