Recipients of HLA-identical sibling marrow transplants with severe aplastic anemia engraft more quickly, and those with chronic myeloid leukemia more slowly, than those with acute leukemia.

An analysis of the rate of leukocyte reconstitution in 164 recipients of HLA-identical sibling marrow transplants showed two factors to be independently influential. These were the underlying diagnosis and the type of prophylactic regimen used to minimize the risk of graft-versus-host disease. Patients with severe aplastic anemia had a faster rate of reconstitution of the total white blood cell count to levels of both 500 and 1000 x 10(6)/l than patients with acute non-lymphoblastic leukemia (ANL), acute lymphoblastic leukemia (ALL) or chronic myeloid leukemia (CML). Patients with severe aplastic anemia (SAA), however, did not show a faster rate of reconstitution of blood neutrophils. As well as being slower than patients with SAA for total leukocyte reconstitution, patients with CML were slower than patients with ANL and ALL in attaining a neutrophil count of 500 x 10(6)/l, and slower than patients with ANL in attaining a neutrophil count of 1000 x 10(6)/l. Patients given cyclosporin as the sole immunosuppressant prophylactic regimen post-transplant had faster reconstitution to total leukocyte counts of 500 and 1000 x 10(6)/l and to neutrophils of 1000 x 10(6)/l than patients given methotrexate alone, methotrexate and cyclosporin, or cyclosporin and T cell depletion of the donor marrow. No other factors (including the pretransplant preparative regimen) were significant in influencing the rate of leukocyte or neutrophil reconstitution. When only patients given cyclosporin were analysed, those with severe aplastic anemia continued to show a faster rate of leukocyte reconstitution to WBC 500 x 10(6)/l compared to patients with ANL, ALL or CML, and a faster rate to WBC 1000 x 10(6)/l than patients with CML.(ABSTRACT TRUNCATED AT 250 WORDS)