title: Thymic factors regulating DNA synthesis in lymphocytes cultured in vitro.
abstract: An extract was prepared from the calf thymus. Thymic factors with stimulating or inhibiting effect on the incorporation of 3H-thymidine into DNA of cultured lymphocytes from guinea pigs and rats were identified and separated from each other by ultrafiltration, gel filtration, ion-exchange chromatography and electrofocusing. Two different stimulating substances were found both with molecular weight below 10,000 daltons. The result of ion-exchange chromatography and preparative electrofocusing indicated the existence of one (or two) acidic and one slightly alkaline stimulating thymic factor. The stimulating substances were found in greater amount in a young thymus than in a an old one. the thymic factors increasing the uptake of 3H-thymidine are probably polypeptides.
mesh_terms: D002470:Cell Survival; D002478:Cells, Cultured; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004247:DNA / Q000096:biosynthesis*; D007525:Isoelectric Focusing; D008214:Lymphocytes / Q000378:metabolism*; D008970:Molecular Weight; D009928:Organ Specificity; D013936:Thymidine / Q000378:metabolism; D013950:Thymus Gland / Q000502:physiology*; D014462:Ultrafiltration
chemical_list: D004247:DNA; D013936:Thymidine