title: T cell antigen receptor expression by subsets of Ly-2-L3T4- (CD8-CD4-) thymocytes.
abstract: The V beta 8-specific mAb F23.1 and KJ16 were used as fluorescent stains to test for TCR expression on the surface of subpopulations of early, CD4-CD8- (L3T4-Ly-2-) thymocytes from adult CBA mice. A surprisingly high proportion (27%) of Ly-2-L3T4- thymocytes were strongly F23.1 and KJ16 positive. No positive cells were detected among Ly-2-L3T4- thymocytes from V beta 8-negative SJL mice. In contrast to the adult thymus, Ly-2-L3T4- cells from embryonic CBA thymus lacked F23.1-positive cells. Subsets of adult CBA Ly-2-L3T4- thymocytes were separated to determine which expressed V beta 8. The major subset, Ly-1 low B2A2-M1/69+Thy-1+Pgp-1-, representing a phenotype similar to embryonic Ly-2-L3T4- thymocytes and the phenotype commonly isolated from adult thymocytes as Ly-1 "dull," lacked cells strongly positive for F23.1. In contrast, a series of subsets of adult CBA Ly-2-L3T4- thymocytes which were B2A2-M1/69- and Pgp-1+ all included strongly F23.1-positive cells. A minor subset, negative for most markers except Pgp-1 and presumed on the basis of this phenotype and some reconstitution studies to include the earliest intrathymic precursors, contained 28% F23.1-positive cells. However, no F.23.1-positive cells were detected in equivalent "prethymic" populations from bone marrow or from athymic mouse spleen. The subsets of Ly-2-L3T4- thymocytes which were Ly-1 high, B2A2-M1/69-, and Pgp-1+ all contained about 70% F23.1-positive cells, indicating a V beta 8 usage much higher than the mature T cell average. These results indicate that a series of distinct developmental events have occurred within these CD4-CD8- thymocytes previously considered as a single group of early precursor cells, and that some aspects of repertoire selection may be occurring amongst thymocytes which lack CD4 or CD8.
mesh_terms: D000375:Aging; D000818:Animals; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D000950:Antigens, Ly / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis; D002460:Cell Line; D004622:Embryo, Mammalian; D005456:Fluorescent Dyes; D006412:Hematopoietic Stem Cells / Q000032:analysis; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis; D051379:Mice; D008808:Mice, Inbred CBA; D008819:Mice, Nude; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000032:analysis*; D016201:Receptors, Lymphocyte Homing; D013194:Staining and Labeling; D013601:T-Lymphocytes / Q000032:analysis / Q000145:classification* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000950:Antigens, Ly; D000954:Antigens, Surface; D005456:Fluorescent Dyes; D008562:Membrane Glycoproteins; D011948:Receptors, Antigen, T-Cell; D016201:Receptors, Lymphocyte Homing