Growth Characteristics of a Transferable Acute Leukemia in Rats 1.2

SUMMARY-After intravenous transfer of leukemia cells, growth of acute myelomonocytic leukemia was mainly in the bone marrow and spleen of rats. All organs became involved later, particularfy when many leukemia cells appeared in the peripheral blood. After injection of 107 leukemia cells, doubling time of absolute numbers of blast cells in the bone marrow was about 30 hours, and of the leukemia blast cells in peripheral blood was shorter, with a minimum of about 6 hours. However, neither estimate represents the true generation time of the leukemia blast cells, because loss of cells from bone marrow and influx From various organs to the blood occurred. The course of the leukemia was predictable, with the easily determined leukocyte count and spleen weight reliable indicators of its severity. There was a strong correlation between growth of the leukemia and the number of cells injected: A time lag of 25-30 hours occurred in the appear-ance of leukemia cells in the peripheral blood For each tenFold reduction in the number of cells injected, Followed by a similar sigmoid curve For all groups. Neither age (4 wk-1 yr) nor weight (55-.400 g) signifi-cantly affected the growth paHern of the leukemia. Survival ranged from 6 to 7 days aFter transFer of 107 leukemia cells to 12-13 days after 1 ()2 leukemia cells.-J Natl Cancer Inst 50: 1321-1327, 1973. EXPERIMENTAL LEUKEMIAS suitable for controlled study are valuable as models for th