The marrow colony forming cell and serum colony stimulating factor of the chicken.

: Marrow cells of the chicken produced colonies in semisolid media. Developing colonies consisted of granulocytes, macrophages or a mixture of these two cell types. The granulocyte-macrophage CFC was nonadherent. An adherent 'CFC' was also present and it differed in several ways from the nonadherent CFC: (a) clones contained only macrophages, (b) they contained a core of nonrefractile cells, (c) their appearance was delayed 1-2 weeks, (d) they were unaffected by the presence of erythrocytes and (e) the efficiency of cloning was increased but the percentage of clones able to produce 50 or more cells was markedly decreased, i.e., the cluster/colony ratio was increased. The growth of both colony types was strictly dependent on the presence of CSF. Data obtained from dose-response studies on unfractionated marrow indicated that clusters and colonies were derived from single cells. The CSF of chicken serum yielded sigmoid dose-response curves when tested on marrow cells. Calf serum could not support cluster or colony formation when tested alone but it did have an enhancing effect on the CSF of chicken serum. Levels of serum CSF were increased by injecting chickens with bacterial endotoxin. This phenomenon occurred with five chicken lines tested, but certain chickens of the Kimber line did not respond to endotoxin with elevated levels of CSF.