title: Interleukin-7 promotes the generation of phenotypically mature CD45RA positive human thymocytes in vitro.
abstract: IL-7 has been shown to support the proliferation of several cell types including human and murine thymocytes. We have investigated the influence of IL-7 on human thymocyte growth and maturation. In a serum-free culture system, recombinant human interleukin-7 (IL-7) (200 U/ml) stimulated nylon wool purified human thymocytes to express a mature phenotype. IL-7 promoted the generation of a population of large thymocytes which expressed high density CD3, CD4 and/or CD8, and high density CD45RA after 10 to 14 days in culture. The induction of CD45RA was not a transient event, since large CD45RA+ cells remained "bright" CD45RA+ up to 12 days after IL-7 was removed from cultures. IL-7 did support thymocyte proliferation. However, the IL-7-induced generation of large CD45RA+ thymocytes was not due to proliferation of a small subset because large CD45RA+ thymocytes also appeared in the presence of proliferation inhibitors. In order to identify IL-7-responsive thymocyte subsets, highly purified CD45RA- subsets at distinct stages of maturation were tested. CD3-, "dim" CD3+ and "bright" CD3+ subsets each responded to IL-7 with de novo expression of CD45RA. These data provide evidence that IL-7 supports phenotypic changes in both mature and immature subsets of human thymocytes, and indicate that IL-7 may play an important role in T cell development in the thymus.
authors.affiliation: Department of Microbiology & Immunology, Center for Interdisciplinary Research in Immunologic Diseases (CIRID), UCLA School of Medicine 90024-1747.
authors.forename: L W
authors.initials: LW
authors.lastname: Vollger
authors.forename: C H
authors.initials: CH
authors.lastname: Uittenbogaart
mesh_terms: D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D002454:Cell Differentiation / Q000276:immunology; D002478:Cells, Cultured / Q000187:drug effects; D002675:Child, Preschool; D016895:Culture Media, Serum-Free; D006801:Humans; D007223:Infant; D015851:Interleukin-7 / Q000276:immunology* / Q000494:pharmacology; D017493:Leukocyte Common Antigens / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000494:pharmacology; D016176:T-Lymphocyte Subsets / Q000187:drug effects; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*
chemical_list: D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D016895:Culture Media, Serum-Free; D015851:Interleukin-7; D011994:Recombinant Proteins; D017493:Leukocyte Common Antigens