Elimination of leukemic cells from rat bone marrow using antibody and complement

An animal model has been developed that utilizes antibody and complement to eliminate a transplantable cloned line of Wistar/Furth acute nonlymphocytic leukemia (CI-3) from syngeneic Wistar/Furth bone marrow. The CI-3 leukemia grows progressively from an i.v. inoculum of 10(1) to 10(2) cells. Antiserum has been raised in rabbits following multiple injections of CI-3. Using optimal concentrations of absorbed antibody and complement, approximately 3 logs of tumor could be destroyed in vitro, judged by the number of cells required to produce progressive growth in vivo. Similar incubation with antibody and complement did not affect the ability of Wistar-Furth marrow to reconstitute rats that had received lethal total-body irradiation (950 R). Each of the 33 irradiated rats that received mixtures of 10(4) CI-3 and 1.6 X 10(8) nucleated bone marrow cells succumbed to leukemia within 65 days, whereas 16 of 33 rats (48%) receiving similar inocula that had been treated with antibody and complement survived greater than 180 days without evidence of tumor growth. Repeated treatment of contaminated marrow with antibody and complement following removal of mature granulocytes and erythrocytes on density gradients permitted elimination of 10(5) CI-3.