LOW-DOSE DONOR CD8(-DEPLETED GRAFT PREVENT ALLOGENEIC MARROW GRAFT-REJECTION AND SEVERE GRAFT-VERSUS-HOST DISEASE FOR CHRONIC MYELOID-LEUKEMIA PATIENTS IN FIRST CHRONIC PHASE() CELLS IN THE CD4)

Based on previous experiences in animals and humans, low doses of CD8( +) lymphocytes infused together with the marrow graft seem to enhance engraftment after allogeneic T cell-depleted marrow transplantation. F rom April 1994 to February 1997, 12 patients with chronic myelogenous leukemia in first chronic phase receiving a bone marrow transplant (BM T) from an HLA-identical sibling were included in a pilot study of T c ell subset depletion. Total depletion of CD4(+) cells of the marrow gr aft and partial depletion of CD8(+) cells was performed by immunomagne tic separation. In order to improve the engraftment rate, we infused a low fixed number of CD8(+) lymphocytes (0.25 x 10(6)/kg). All the pat ients were at high risk of developing acute graft-versus-host disease (GVHD), with a recipient age of >30 years, and/or donor sensitized by previous pregnancies or transfusions. All of them received cyclosporin A and methotrexate post-BMT. No graft failure was observed. The grade III-IV GVHD rate was 16.6%, and the actuarial survival at 3 years is 81.8%. Immunological recovery showed persistent CD8(+) HLA-DR+ lymphoc ytosis 8 months after transplant. Relapses were not observed. This exp erience shows the importance of CD8(+) cells to ensure correct engraft ment, decreasing the GVHD rate.