PROLIFERATIVE STATE OF NORMAL INVITRO COLONY-FORMING CELLS DURING DEVELOPMENT OF L5222 RAT LEUKEMIA AND THEIR REACTION TO CHEMOTHERAPY

  • 1 January 1978
    • journal article
    • research article
    • Vol. 51  (2) , 221-227
Abstract
In the experimental rat leukemia, L5222, the decrease of normal in vitro colony-forming cells (CFU-C) after chemotherapy with daunomycin was much less than in nonleukemic controls. The L5222 leukemia has the advantage that the leukemic blast cells do not form colonies in agar culture so that normal CFU-C can be assessed under leukemic conditions. To compare the proportions of CFU-C in the S-phase in normal and leukemic rats, 2 S-phase-specific agents, 3H-thymidine and hydroxyurea, were used to kill proliferating bone marrow cells. Following treatment with 3H-thymidine in vitro, about 41% of the CFU-C were killed in normal and about 25% in leukemic bone marrow. Hydroxyurea administered in vivo resulted in the death of about 33% and 26%, respectively. Fewer normal CFU-C apparently are in S-phase in the L5222 leukemia, which might help to explain how enough normal stem cells survive chemotherapy to regenerate the bone marrow.