title: Alpha/beta T-cell antigen receptor gene and protein expression occurs at early stages of thymocyte differentiation.
abstract: Alterations in gene expression that orchestrate eukaryotic cellular differentiation often require appropriate interactions between differentiating cells and a specialized microenvironment. During T-lymphocyte differentiation, immature thymocytes undergo a stringent intrathymic selection process that requires intimate contact with thymic stromal elements. Since this selection process generates T cells that are self-tolerant and recognize nominal antigen only within the context of self-major histocompatibility antigen complex molecules, it is possible that thymocyte/stromal cell interactions are mediated, in part, by antigen-specific receptors expressed on differentiating thymocytes. However, the developmental stage at which alpha/beta antigen-specific receptors are expressed during T-cell maturation has been a matter of debate. To address this issue, we have studied alpha/beta T-cell antigen receptor gene and protein expression on normal thymocyte subsets of AKR/J mice, as well as on a panel of AKR/J primary thymic lymphomas characterized for CD4 (L3T4) and CD8 (Lyt-2) differentiation antigen expression. The data unequivocally demonstrate that alpha/beta heterodimers are expressed not only on phenotypically mature thymocytes but also on the majority of CD4+8+ double-positive cells that comprise the predominant nonmature thymocyte subset. Furthermore, a fraction of thymocytes in the CD4-8- double-negative compartment, known to contain progenitor cells, also expresses readily detectable cell-surface alpha/beta receptors. Therefore, during the process of intrathymic selection, interactions between nonmature thymocytes and stromal cells via the antigen-receptor complex may play a pivotal role in T-cell differentiation and should be considered in formulating schemes for functional T-cell selection.
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D000951:Antigens, Neoplasm / Q000032:analysis; D002454:Cell Differentiation; D005786:Gene Expression Regulation; D008223:Lymphoma / Q000276:immunology / Q000473:pathology; D051379:Mice; D008806:Mice, Inbred AKR / Q000235:genetics / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000096:biosynthesis / Q000235:genetics*; D016693:Receptors, Antigen, T-Cell, alpha-beta; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology* / Q000473:pathology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta