title: Interleukin-7 treatment promotes the differentiation pathway of T-cell-receptor-alpha beta cells selectively to the CD8+ cell lineage.
abstract: In this report we have studied the influence of interleukin-7 (IL-7) on thymocyte differentiation by evaluating the effects of IL-7 on the generation of T-cell receptor-alpha beta (TCR-alpha beta) and TCR-gamma delta thymocyte subpopulations in rat fetal thymus organ culture. IL-7 enhanced the differentiation pathway of TCR alpha beta thymocytes, first increasing the numbers of immature CD8+ cells, and later those of both CD4+ CD8+ and mature thymocytes. The kinetics of thymocyte migration out of thymic lobes was also accelerated, and the average number of mature TCR-alpha beta phi emigrants per day was increased in the presence of IL-7. Moreover, mature CD4- CD8+ thymocytes were preferentially generated after IL-7 administration. This TCR-alpha beta hi cell population was not actively dividing, indicating that IL-7-promoted thymocyte differentiation was selective to the CD8 cell lineage. Distribution of some TCR-V alpha and TCR-V beta segments among mature thymocytes was also modified in IL-7-treated thymic lobes. On the contrary, the maturation of TCR-gamma delta was not affected by IL-7 addition during the first days of culture, but their numbers sharply increased by day 6 of culture. These results were confirmed with IL-7-treated cultures for 24 hr, showing that IL-7 responsiveness was acquired by TCR-gamma delta cells late in thymus ontogeny. The present results thus indicate a key role for IL-7 in the maturation of TCR-alpha beta thymocytes and the expansion of thymic TCR-gamma delta cells.
authors.affiliation: Department of Cell Biology, Faculty of Biology, Complutense University, Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Varas
authors.forename: A
authors.initials: A
authors.lastname: Vicente
authors.forename: E
authors.initials: E
authors.lastname: Jiménez
authors.forename: L
authors.initials: L
authors.lastname: Alonso
authors.forename: J
authors.initials: J
authors.lastname: Moreno
authors.forename: J J
authors.initials: JJ
authors.lastname: Muñoz
authors.forename: A G
authors.initials: AG
authors.lastname: Zapata
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002453:Cell Cycle / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D002465:Cell Movement / Q000276:immunology; D016130:Immunophenotyping; D015851:Interleukin-7 / Q000276:immunology*; D007958:Leukocyte Count; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis*; D013950:Thymus Gland / Q000196:embryology / Q000276:immunology; D013997:Time Factors
chemical_list: D015851:Interleukin-7; D016693:Receptors, Antigen, T-Cell, alpha-beta