title: Assessment of CD4 expression by early T precursor cells and by dendritic cells in the human thymus.
abstract: The adult mouse thymus contains a minute population of early lymphoid precursor cells that express moderate levels of CD4. We searched for a corresponding population of early T precursors in the infant human thymus, by first depleting the majority of more mature thymocytes, then using immunofluorescence and flow cytometry to analyze cells bearing a range of early T lineage markers. No discrete population of early T precursors expressing CD4 was observed, in contrast to the murine thymus. Most putative very early human thymocytes were CD4-8-3-1-2lo44+34+7hi class I MHChi class II MHC-. However, a distinct population of human thymic dendritic cells expressing high levels of CD4 was isolated. These were CD4hi8-3-1-2-44+34-7- class I MHChi class II MHChi, and lacked markers of B cells, NK cells, or myeloid cells. They were large cells that exhibited dendritic morphology after brief periods of culture, and they were efficient stimulators of allogeneic T cells. The biologic implications of CD4 expression by thymic dendritic cells are discussed.
authors.affiliation: Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.
authors.forename: F
authors.initials: F
authors.lastname: Sotzik
authors.forename: Y
authors.initials: Y
authors.lastname: Rosenberg
authors.forename: A W
authors.initials: AW
authors.lastname: Boyd
authors.forename: M
authors.initials: M
authors.lastname: Honeyman
authors.forename: D
authors.initials: D
authors.lastname: Metcalf
authors.forename: R
authors.initials: R
authors.lastname: Scollay
authors.forename: L
authors.initials: L
authors.lastname: Wu
authors.forename: K
authors.initials: K
authors.lastname: Shortman
mesh_terms: D000293:Adolescent; D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D019011:Antigens, CD7; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D018801:CD2 Antigens; D017252:CD3 Complex / Q000032:analysis; D015704:CD4 Antigens / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology*; D016827:CD8 Antigens / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D003713:Dendritic Cells / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000032:analysis; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D011971:Receptors, Immunologic / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D019011:Antigens, CD7; D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D015395:Histocompatibility Antigens Class I; D011971:Receptors, Immunologic