title: A microassay for colony-stimulating factor based on thymidine incorporation.
abstract: A variety of growth factors and lectins were tested; only colony-stimulating factors CSF-1, Interleukin 3, and a T-lymphocyte GM CSF induced colony formation in semisolid medium and stimulated thymidine incorporation in liquid culture. All other growth factors and lectins were inactive in both assays. Factor-stimulated thymidine incorporation was detectable 24 hours after stimulation and reached maximal levels 4-6 days after stimulation. A convenient microassay for measuring CSF activity has been developed, enabling a large number of samples to be screened qualitatively in 2 days and permitting CSF activity to be measured quantitatively in 4-5 days. This microassay can supplement the clonal-cell assay method and be especially useful as an initial screening assay for CSF activity.
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D002999:Clone Cells / Q000378:metabolism; D003114:Colony-Forming Units Assay; D003115:Colony-Stimulating Factors / Q000096:biosynthesis / Q000502:physiology*; D003470:Culture Media; D006133:Growth Substances / Q000502:physiology; D051379:Mice; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D013601:T-Lymphocytes / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism*
chemical_list: D003115:Colony-Stimulating Factors; D003470:Culture Media; D006133:Growth Substances; D013936:Thymidine