WBC transfusions are being used for treatment of infections not responding to antibiotics in patients with severe leukopenia due to acute leukemia or bone marrow depression. The AABB recommends 500 granulocytes/mm3 (or per microliter) as the cutoff point defining severe leukopenia. Clinical improvement has been reported in some of these patients but not all. Most large blood banks have the equipment to offer granulocyte transfusion as a routine procedure. The granulocytes are usually collected by apheresis methods and stored at room temperature. The AABB recommends that granulocytes be transfused within 24 hours after collection. According to the AABB, a daily dose of at least 1 x 1010 functional granulocytes appears necessary. Each granulocyte concentrate dose also contains 3 x 1011 platelets. The same recommendations regarding irradiation noted above for platelet concentrates also applies to granulocytes.