title: Ontogeny of interleukin 2 responsive cells in the fetal thymus.
abstract: The ontogeny of IL 2-responsive cells in the thymus of CBA/J mice was examined in neonatal animals and in fetuses at 14, 16, and 18 to 20 days gestation. The thymocytes were tested for responsiveness to 2 micrograms/ml Con A, TCGF, IL 2, and co-stimulation by Con A plus TCGF or IL 2. These responses were compared with those of thymocytes of 6- to 8-wk-old CBA/J. Thymocytes (1 X 10(5)) were cultured, and the reaction was measured at maximum response (96 hr). Neonatal animals gave an unusually high response to TCGF or partially purified IL 2 alone, approximately five times greater than the adult. A low but significantly enhanced proliferation, stimulated by partially purified IL 2 alone, was observed with 14-day fetal thymocytes, even though cultures of these cells in medium alone had higher background proliferation than any other age tested. In the co-stimulator reaction, proliferation significantly above background was measured at 16 days of gestation with Con A plus TCGF. The magnitude of the co-stimulator reaction increased with age, especially between the 16th and 18th day of gestation and immediately after birth.
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D003208:Concanavalin A / Q000494:pharmacology; D005260:Female; D007376:Interleukin-2 / Q000502:physiology*; D051379:Mice; D008808:Mice, Inbred CBA; D011247:Pregnancy; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology*
chemical_list: D007376:Interleukin-2; D003208:Concanavalin A