title: Expression patterns of Ikaros family members during positive selection and lineage commitment of human thymocytes.
abstract: The Ikaros family of transcription factors is essential for normal T-cell development, but their expression pattern in human thymocytes remains poorly defined. Our goal is to determine how protein levels of Ikaros, Helios and Aiolos change as human thymocytes progress through the positive selection and lineage commitment stages. To accomplish this goal, we used multi-parameter flow cytometry to define the populations in which positive selection and lineage commitment are most likely to occur. After human thymocytes express CD3 and receive positive selection signals, the cells down-regulate expression of CD4 to become transitional single-positive (TSP) CD8+thymocytes. At this stage, there was a transient increase in the Ikaros, Helios and Aiolos protein levels. After the TSP CD8+developmental stage, some thymocytes re-express CD4 and become CD3hidouble-positive thymocytes before down-regulating CD8 to become mature single-positive CD4+thymocytes. Except for regulatory T cells, Helios protein levels declined and Aiolos protein levels transiently increased during CD4+T-cell maturation. For thymocytes progressing toward the CD8+T-cell lineage, TSP CD8+thymocytes increase their expression of CD3 and maintain high levels of Aiolos protein as the cells complete their maturation. In summary, we defined the TSP CD8+developmental stage in human T-cell development and propose that this stage is where CD4/CD8 lineage commitment occurs. Ikaros, Helios and Aiolos each undergo a transient increase in protein levels at the TSP stage before diverging in their expression patterns at later stages.
authors: Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS, USA.
authors: Julie L
authors: JL
authors: Mitchell
authors: Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS, USA.
authors: Amara
authors: A
authors: Seng
authors: Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS, USA. tyankee@kumc.edu.
authors: Thomas M
authors: TM
authors: Yankee
mesh_terms: D000293:Adolescent; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation; D019070:Cell Lineage; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D060966:Clonal Selection, Antigen-Mediated; D006801:Humans; D051740:Ikaros Transcription Factor / Q000378:metabolism*; D007223:Infant; D007231:Infant, Newborn; D060168:Thymocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology*
chemical_list: C497239:IKZF1 protein, human; C111431:IKZF2 protein, human; C106285:IKZF3 protein, human; D051740:Ikaros Transcription Factor
keywords: Ikaros; T-cell development; human; thymus