Neutropenia is the major factor predisposing to sepsis in cancer patients, and its duration is important for survival. We administered leukocyte transfusions (LT) to 10 children suffering from documented life-threatening infections during profound, prolonged neutropenia. Nine had acute leukemia, and one had aplastic anemia; three were bone marrow transplant recipients. These 10 were the only patients in our unit who received LT during the past 7 years. The median leukocyte dose was 0.6x10^9/kg in total. Instead of leukapheresis products, we used pooled buffy coats from random donors, with a high relative content of lymphocytes and especially T lymphocytes. The leukocyte concentrates were irradiated with 15 Gy. In all 10 patients, we observed prompt and sustained myeloid marrow recovery following LT. Such an effect of LT has never been described before. We hypothesize that in the internal milieu of these aplastic patients the transfused leukocytes were stimulated to secrete cytokines, the result being a cascade-like phenomenon and stimulation and proliferation of the patient’s own bone marrow cells. The bone marrow-stimulating effect of LT merits further study.

For purposes of freezing autologous marrow or transplants of allogeneic marrow with major ABO blood group incompatibility, 54 freshly harvested bone marrows from children of 7-65 kg of weight were depleted of their red cells with the Haemonetics V50 system. The marrow volumes ranged from 230 to 1,145 ml, with 17 small (200-399 ml), 18 intermediate (400-799 ml) and 19 large (800-1,200 ml) volumes. After processing, the median recoveries were: volume 24%, red cell mass 18%, and nucleated cells 75%. In the small marrow volume group, a good nucleated cell recovery was achieved at the expense of red cell depletion. The colony-forming units, granulocytes-macrophages (CFU-GM) were normal after thawing of processed, cryopreserved marrows, and good engraftment of both allogeneic and autologous marrows were achieved. We conclude that marrow processing with the Haemonetics V50 system results in adequate red cell depletion and good nucleated cell recovery without open-air contact of marrow or excessive time consumption. For small marrow volumes, however, the red cell depletion was suboptimal, and a bowl size smaller than 125 ml is desirable for pediatric use.