title: Synthesis and release of thymidine by macrophages.
abstract: An inhibitor of DNA synthesis and cell proliferation found in macrophage supernatants was subjected to further analysis. The following conclusions were drawn: a. Biochemically, the inhibitor appeared to be thymidine, judging from the migration in three different thin-layer systems and on gel filtration. b. The inhibitor was shown to be synthesized de novo by macrophage monolayers pulsed with a radiolabeled precursor of thymidine such as 14C-formate. c. The amount of inhibitor present in tissue culture fluids proved to be sufficient to block the growth of the EL-4 leukemia cell line in a manner that could be prevented with the addition of 2'-deoxycytidine. The EL-4 line was considerably more sensitive to thymidine blockade than a number of different cells tested.
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D002850:Chromatography, Gel; D002855:Chromatography, Thin Layer; D003470:Culture Media; D004247:DNA / Q000037:antagonists & inhibitors*; D004261:DNA Replication / Q000187:drug effects; D003864:Depression, Chemical; D005260:Female; D007938:Leukemia / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D051379:Mice; D009374:Neoplasms, Experimental / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D003470:Culture Media; D004247:DNA; D013936:Thymidine