LYMPHOCYTE SUBSET RECONSTITUTION AFTER ALLOGENEIC BONE-MARROW TRANSPLANTATION USING RADIATION-FREE CONDITIONING REGIMEN FOR PATIENTS WITH CHRONIC GRANULOCYTIC-LEUKEMIA

Conditioning regimens for BMT are important in determining transplant outcome. A radiation-free protocol containing Mitobronitol (DBM), Cyta rabine (Ara-C) and Cyclophosphamide (Cy) was used for conditioning of patients with chronic granulocytic leukemia (CGL). Using this conditio ning treatment, fewer transplant related complications, including acut e GVHD, VOD and severe infections, were observed. Acute GVHD did not d evelop, but chronic GVHD, accompanied with graft-versus leukemia, was present in half of the cases. To determine the clinical effect of the DBM/Ara-C/Cy conditioning, the recovery of peripheral blood lymphocyte s was examined after allogeneic BMT for patients with CGL in compariso n with TBI/Cy conditioning. The lymphocyte subsets of 11 DBM patients were followed and analyzed periodically (30-90 days, 4-12 months and > 13 months) using ten monoclonal antibodies and flow cytometry. Decrea sed percentage of total T cells as well as CD4+ and CD8+ subpopulation s, significantly decreased T cell activation and increased proportion of TCR gamma delta+ cells were found to be characteristic in the early post-transplant period in the DBM group. Early recovery and consisten tly higher percentage of B cells were observed for the whole follow-up period of patients receiving DBM conditioning. A high proportion of N K cells was observed in ail transplant recipients. These findings sugg est that the characteristic pattern of recovering lymphotytes is assoc iated with the lack of severe transplant-related clinical complication s following DBM/Ara-C/Cy conditioning.