Regeneration of peripheral blood cells following allogeneic bone marrow transplantation for severe aplastic anaemia.

We have studied the pattern of regeneration of peripheral blood cells following ABO compatible bone marrow transplantation for severe aplastic anaemia. 18 patients were treated with cyclosporin A and six with methotrexate for post graft immunosuppression. The number of days taken for the neutrophil count to reach 0.5 x 10(9)/l, the lymphocyte count to reach 1.0 x 10(9)/l, the platelet count to reach 100 x 10(9)/l and the reticulocytes to reach 1% was shorter in the CyA treated patients. This finding reached statistical significance for all types of cells except the platelets (neutrophils, P less than 0.001; lymphocytes, P less than 0.02; platelets, P greater than 0.05; reticulocytes, P less than 0.001). The more rapid regeneration of peripheral blood cells in patients treated with cyclosporin A has contributed to reducing the length of time patients are dependent on blood product support in the post transplant period.