title: Requirements for growth of immature thymocytes from fetal and adult mice in vitro.
abstract: We report here defined culture conditions that allow reproducibly the growth of the majority of immature thymocytes from both fetal (14-15 days of gestation) and adult mice. The combination of phorbol myristate acetate (PMA), ionomycin and recombinant interleukin 2 (IL2) is both sufficient and necessary to induce growth of about 1/6.2 (range 1/3-1/9) and 1/4.3 (range 1/2-1/7) immature thymocytes from adult and fetal mice, respectively, in serum-free cultures. Several other combinations tested (e.g. PMA + IL2, concanavalin A + IL2) were poorly or not active. None of the agents tested alone (PMA, ionomycin, concanavalin A, pokeweed mitogen, IL2) had any effect. We found no evidence for a role of IL1 and IL3 on growth of these cells. The growth of activated immature thymocytes from either fetal or adult mice was inhibited by a monoclonal antibody against mouse IL2 receptors. Under the same conditions that stimulated growth of most immature thymocytes, they did not mature into cells expressing Lyt-2, L3T4 or T cell antigen receptor (KJ16) after 7 to 15 days of continuous proliferation in culture. Nor did they give rise to cells with cytolytic activity after 7-9 days of culture. In some but not all experiments cultures of immature thymocytes from adult mice but not from fetal mice generated cells (1 out of 120-310) with helper function for B lymphocytes. While we confirmed here that approximately 50-70% freshly isolated immature thymocytes express receptors for IL2, our results indicate that these cells need to be activated (by e.g. PMA + ionomycin) to respond to IL2. A possible mechanism to account for the expression of nonfunctionally competent IL2 receptors is proposed and our results concerning the maturation of immature thymocytes in vitro are discussed.
authors.forename: R
authors.initials: R
authors.lastname: Palacios
authors.forename: H
authors.initials: H
authors.lastname: Von Boehmer
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis; D002454:Cell Differentiation; D002455:Cell Division; D002469:Cell Separation; D002478:Cells, Cultured; D003470:Culture Media; D003602:Cytotoxicity, Immunologic; D006133:Growth Substances; D051379:Mice; D011971:Receptors, Immunologic / Q000276:immunology; D015375:Receptors, Interleukin-2; D013950:Thymus Gland / Q000166:cytology* / Q000196:embryology
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D003470:Culture Media; D006133:Growth Substances; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2