title: Interleukin 2 promotes growth and cytolytic activity in human T3+4-8- thymocytes.
abstract: Human thymocytes bearing T3 but neither T4 nor T8 antigens (T3+4-8- cells) were obtained after negative selection of thymocytes, either fresh or cultured in medium containing recombinant interleukin 2 (IL-2), by treatment with Na1/34, OKT4A and B9.4 monoclonal antibodies (which recognize T6, T4, and T8 antigens, respectively) and complement. Quantitative flow cytometry showed a 98% pure population of T3+4-8- lymphocytes, which included proliferating cells. The growth and maturation requirements of these thymocytes were characterized and related to the T3-receptor complex and IL-2 pathways, thought to be used by mature lymphocytes. The results show that addition of recombinant IL-2 promotes, in a dose-dependent way, proliferation and acquisition of effector functions by cultured T3+4-8- thymocytes, the growth being inhibitable by monoclonal antibody 33B73 (anti-Tac). Furthermore, cytolytic activity of T3+4-8- cells induced by recombinant IL-2 is specifically blocked by monoclonal antibody OKT3, showing that it operates via the T3-receptor complex and does not require either T4 or T8 molecules. The finding of in vitro responsiveness to recombinant IL-2 in T3+4-8- thymocytes suggests a role of IL-2 in the growth and maturation of cells committed to the T-cell lineage, during intrathymic differentiation, prior to expression of T4 and T8 molecules.
mesh_terms: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000276:immunology; D002454:Cell Differentiation; D002455:Cell Division; D005434:Flow Cytometry; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D011971:Receptors, Immunologic / Q000276:immunology; D015375:Receptors, Interleukin-2; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D007376:Interleukin-2; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2