title: Intrathymic differentiation of V gamma 3 T cells.
abstract: Whereas there is considerable information on the phenotypic and functional maturation of T cell receptor (TCR) alpha/beta thymocytes, comparatively little is known of the maturational processes that affect development of TCR-gamma/delta thymocytes. One class of gamma/delta T cells, those bearing the V gamma 3 gene product, are generated only during the early fetal stages of thymic development, and then migrate to the skin. Here we examine the intrathymic differentiation of these V gamma 3+ cells. The earliest V gamma 3 cells to appear in the thymus expressed low levels of TCR (V gamma 3low) and high levels of heat stable antigen (HSA). Over the next few days, V gamma 3+ thymocytes appeared which expressed high levels of TCR (V gamma 3high) and very low levels of HSA. The antigens CD5, CD45RB, and MEL14 were also differentially expressed on V gamma 3low versus V gamma 3high thymocytes, but the shift in expression was the opposite as compared with immature and mature TCR-alpha/beta thymocytes. Transfer experiments of sorted V gamma 3low/HSAhigh thymocytes to SCID thymic lobes showed that these cells were indeed the precursors of V gamma 3high/HSAlow thymocytes. The phenotype of the V gamma 3high thymocytes was similar to that of the postthymic V gamma 3+ cells found in the skin of adult mice. The differentiation of V gamma 3low in V gamma 3high thymocytes was also observed in fetal thymic organ culture. Addition of cyclosporin A (CsA) to these cultures had little effect on the appearance of V gamma 3low/HSAhigh cells, but blocked the appearance of V gamma 3high/HSAlow cells. These results show that, like alpha/beta T cells, V gamma 3+ thymocytes differentiate from TCRlow precursors to cells with a mature phenotype and that CsA inhibits this transition.
authors.affiliation: Laboratory of Bacteriology, Virology and Immunology, University Hospital Gent, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Leclercq
authors.forename: J
authors.initials: J
authors.lastname: Plum
authors.forename: D
authors.initials: D
authors.lastname: Nandi
authors.forename: M
authors.initials: M
authors.lastname: De Smedt
authors.forename: J P
authors.initials: JP
authors.lastname: Allison
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D016572:Cyclosporine / Q000494:pharmacology; D005260:Female; D016130:Immunophenotyping; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D011247:Pregnancy; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis* / Q000235:genetics; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D016692:Receptors, Antigen, T-Cell, gamma-delta; D016572:Cyclosporine