title: CFU-GM colony-enhancing activity in sera of dogs under acute and chronic gamma-irradiation regimens.
abstract: Dogs were chronically irradiated (10 R/day; 0-400 R) or acutely irradiated (20 R/min; 0-400 R) with 60Co gamma-rays. Sera were collected and assayed for colony-enhancing activity by a double-layer agar cloning technique. When test sera alone were incorporated in the feeder layers, no colony-forming units-granulocyte/macrophage formation occurred; the addition of peripheral blood leukocytes to such test sera-containing feeder layers resulted in formation of colonies, the number of which was directly related to the cumulative radiation dose. Serum-enhancing factor activity indirectly increased colony formation by stimulating feeder layer leukocytes to generate increased levels of colony-stimulating activity. Levels of serum-enhancing activity were higher at similar dose levels following acute gamma irradiation then following chronic irradiation.
mesh_terms: D000818:Animals; D003037:Cobalt Radioisotopes; D003115:Colony-Stimulating Factors / Q000097:blood*; D004285:Dogs; D005260:Female; D006098:Granulocytes / Q000528:radiation effects*; D007962:Leukocytes; D008264:Macrophages / Q000528:radiation effects*; D008297:Male; D013234:Stem Cells / Q000528:radiation effects*
chemical_list: D003037:Cobalt Radioisotopes; D003115:Colony-Stimulating Factors