title: Analysis of expression of CD2, CD3, and T cell antigen receptor molecules during early human fetal thymic development.
abstract: To define early stages of T cell maturation during human fetal thymic development, we have used mAb reactive with CD2, CD3, and TCR molecules in indirect immunofluorescence assays on a series of early human fetal thymic specimens. Using a technique of quantitating the relative proportions of fluorescent-positive cells present in tissue sections, we found at 8.5 wk of gestational age after arrival of CD7+ T cell precursors into the thymic rudiment, 60% of thymic CD7+ cells were CD2+, 4% were CD3+ and none was TCR-delta+ or TCR beta+. Moreover, cells reactive with anti-CD2 antibodies against T11(2) and T11(3) epitopes of CD2 as well as thymic stromal cells expressing the CD2 ligand, lymphocyte function associated Ag-3, were also present at 8.5 wk. From 9.5 wk to birth TCR beta+ cells increased to include greater than 90% of all CD7+ cells while TCR-delta+ cells fell from a peak of 11% of CD7+ cells at 9.5 wk to 1% of CD7+ cells at birth. These data suggest that epitopes of CD2 molecules are expressed early on during fetal thymic development. Moreover, these data suggest that CD7+, CD2+, cytoplasmic CD3+ T cell precursors in man give rise to both TCR-delta+ T cells as well as to T cells expressing TCR-alpha beta.
mesh_terms: D000911:Antibodies, Monoclonal; D000937:Antigen-Antibody Reactions; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D018801:CD2 Antigens; D017252:CD3 Complex; D005314:Embryonic and Fetal Development; D005865:Gestational Age; D006801:Humans; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000032:analysis*; D011971:Receptors, Immunologic / Q000032:analysis*; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology / Q000502:physiology; D013950:Thymus Gland / Q000254:growth & development / Q000276:immunology* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic