1. Eight transfusions of leukemic blood containing up to 143 billion mononuclear cells were rapidly infused into 5 nonleukemic cancer-bearing recipients. Each transfusion was followed by a transient rise in the recipients’ leukocyte count which was less than anticipated by dye dilution methods in five experiments. The observed rise was due entirely to an increase in the mononuclear cell count. The data from two experiments were considered unreliable and were not reported with regard to the behavior of the white cells.
2. The data are interpreted as demonstrating removal of leukemic leukocytes from the recipient’s blood in the pulmonary circulation.
3. A reaction resembling anaphylaxis occurred following one transfusion of leukemic cells, and was associated with an immediate profound leukopenia. It is suggested that the sudden removal in the lesser circulation of a volume of white cells estimated at 40 cc. may have caused the severe observed respiratory and circulatory symptoms.
4. Sustained eosinophilia of unknown etiology was observed following transfusions of leukemic cells in 2 recipients.
5. Hematologic and clinical observation indicated that leukemia was not transferred to any recipient during the short period of observation that followed.