title: IL-2 receptor inducibility is blocked in cortical-type thymocytes.
abstract: Activation of mature T cells induces the expression of high affinity receptors for the T cell growth hormone, IL-2. A short term assay was used to determine the capacity of murine thymocyte subpopulations to express the gene encoding the 55-kDa chain of the IL-2R after stimulation in vitro. Thymocytes were cultured in the presence or absence of phorbol ester and calcium ionophore for 20 h, stained with antibodies against the IL-2R or the MHC Ag, H-2K, and analyzed by FACS. At least 90% of CD4-CD8- thymocytes were competent to express IL-2R, implying that this functional response is acquired early in development. However, at least 80% of cortical thymocytes were unable to express IL-2R before or after stimulation. Additional fractionation of the nonresponsive cells indicated that they constitute the great majority of the CD4+CD8+ population, including virtually all of the CD4+CD8+ proliferating blasts. Most nonresponsive cells remain viable and react to the chemical stimuli by increasing their surface expression of H-2K. The inability of most cortical thymocytes to express IL-2R suggests that a discrete loss of function occurs in most cells as they differentiate from CD4-CD8- precursors into the CD4+CD8+ class. The inferred loss of function is mediated at the level of IL-2 RNA accumulation and may be correlated with a pleiotropic alteration in physiologic response pathways.
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D000001:Calcimycin / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D008213:Lymphocyte Activation; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000235:genetics; D015375:Receptors, Interleukin-2; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D000001:Calcimycin; D013755:Tetradecanoylphorbol Acetate