title: Kinetics of mature T-cell development in the thymus.
abstract: We have reexamined the balance between cell birth, cell maturation, and cell death in the thymus by labeling dividing thymocytes and their progeny in vivo with [3H]-thymidine, isolating clearly defined subpopulations by fluorescence-activated cell sorting, and determining the distribution of label by autoradiography. When mature thymocytes were precisely defined (as CD4+CD8- CD3+ or CD4-CD8+ CD3+) and separated from immature single positives (CD4+CD8- CD3- and CD4-CD8+ CD3-), a lag was observed in the rate of entry of [3H]thymidine into mature cells. Thus, many of the mature thymocytes appear to derive from a small nondividing cortical thymocyte pool, rather than originating directly from the earliest dividing CD4+CD8+ blasts. There was little evidence for cell division during or after mature thymocyte formation, suggesting a one-for-one differentiation from cortical cells rather than selective clonal expansion. The rate of production of mature single positive thymocytes agreed closely with estimates of the rate of export of mature T cells from the thymus and was only 3% of the rate of production of double-positive cortical thymocytes. This was compatible with a stringent selection process and extensive intrathymic cell death and suggested that no extensive negative selection occurred after the mature cells were formed.
authors: Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.
authors: M
authors: M
authors: Egerton
authors: R
authors: R
authors: Scollay
authors: K
authors: K
authors: Shortman
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D017252:CD3 Complex; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens; D002455:Cell Division; D004261:DNA Replication; D007700:Kinetics; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D013936:Thymidine / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*; D014316:Tritium
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D011948:Receptors, Antigen, T-Cell; D014316:Tritium; D013936:Thymidine