Growth of granulopoietic bone marrow cells of RF mice.

Mice of the RF strain are unusually susceptible to the development of leukemia, both spontaneously and after whole body irradiation. Cell culture and transplantation techniques were used to study the proliferative capacity of hematopoietic tissues of these mice. The growth characteristics of granulopoietic cells of young, non-irradiated RF mice were compared with those from a leukemia-resistant strain, C57BL/6J (B6). Marrow from RF mice showed a substantial reduction in the number of colony-forming units in culture (CFUC). The numbers of marrow cells capable of forming colonies in the spleen of lethally irradiated syngeneic mice (CFUS) were also reduced. The spleens from non-irradiated RF mice were almost twice the size of those from B6 mice. Despite these differences the numbers of circulating peripheral leukocytes and percent of polymorphonuclear leukocytes were similar in the two strains. Bone marrow from RF mice may be analogous to that of certain human "preleukemic" states in which alterations in marrow cells are demonstrable in culture.