title: Induction of TCR-gamma delta expression on triple-negative (CD3-4-8-) human thymocytes. Comparative analysis of the effects of IL-4 and IL-7.
abstract: It is well established that IL-4 and IL-7 control the differentiation of TCR-gamma delta-expressing cells from CD3/TCR-negative thymic precursors. In this study, we have compared the in situ expression of IL-4 and IL-7 mRNA in human postnatal thymus with the in vitro effect of IL-4 and IL-7 on the expansion of TCR-gamma delta + cells from highly purified CD3-4-8- triple-negative thymocytes. IL-4 mRNA expression was restricted to subcapsular regions of the human thymus, whereas cells expressing IL-7 mRNA were distributed throughout the thymic tissue, with some enrichment in subcapsular and cortical regions. Epithelial cells of the outer layer of Hassall's corpuscle strongly expressed IL-7 mRNA. IL-7 but not IL-4 or IL-2, stimulated strong proliferative activity and cellular expansion of triple-negative thymocytes. All three induced the appearance of TCR-gamma delta + cells within 4 days of culture. In the presence of IL-4 or IL-2, 30 to 55% of viable cells were TCR-gamma delta + after 5 to 9 days, whereas only 10 to 15% triple-negative thymocytes cultured with IL-7 expressed TCR-gamma delta. However, comparable absolute numbers of viable TCR-gamma delta + thymocytes were recovered when triple-negative thymocytes were cultured with IL-4 or IL-7, but not with IL-2. Taken together, our results suggest that IL-4 and IL-7 (both of which are produced in situ in thymic tissue) play equally important roles in the in vitro generation of TCR-gamma delta + thymocytes from triple-negative precursor cells.
authors.affiliation: Institute of Immunology and Serology, University of Heidelberg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: He
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Deng
authors.forename: D
authors.initials: D
authors.lastname: Kabelitz
mesh_terms: D015870:Gene Expression; D006801:Humans; D016130:Immunophenotyping; D015847:Interleukin-4 / Q000235:genetics / Q000494:pharmacology*; D015851:Interleukin-7 / Q000235:genetics / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D015851:Interleukin-7; D012333:RNA, Messenger; D016692:Receptors, Antigen, T-Cell, gamma-delta; D015847:Interleukin-4