[Helper T cell paradigm: Th17 and regulatory T cells involved in autoimmune inflammatory disorders, pathogen defense and allergic diseases].
The helper T cell paradigm, divided into two distinct subsets, Th1 and Th2 cells, characterized by distinct cytokine and functions, has been expanded to IL-17-producing Th17 cells. Th1 cells producing IFN-γ are involved in delayed-type hypersensitivity, effective in intracellular pathogens defense, while Th2 cells secrete IL-4, IL-5, IL-13 and IL-25 and has a central role in IgE production, eosinophilic inflammation, and the protection for helminthic parasite infection. Th17 cell lineages, expressing IL-17 family of cytokines and IL-23-mediated functions on T cells, plays a role in immune response to fungi and extracellular pathogens and autoimmune inflammatory disorders. Th17 cells are required the combination of IL-6 and TGF-β and the transcription factors, RORC2/RORgt (mice) and STAT3 for differentiation, and produce IL-17, IL-22, IL-17F, IL-21 and CCL20. FOXP3+ regulatory T (Treg) cells produce TGF-β and IL-10, which regulate effector T cells, and thus maintain peripheral tolerance. Four functionally unique CD4+ T cells, including the regulatory T (Treg) cells are now involved in the regulation of immune responses to pathogens, self-antigens and allergens. Any defect in the entire CD4+T cell population might results in human diseases. In this review, the biology of Th17 cells and Treg cells and their role in immune diseases are presented.
Kitasato University Graduate School of Medical Science, Department of Pediatrics, Sagamihara, Kanagawa, Japan.
Takeshi
T
Noma
D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology*; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007239:Infections / Q000276:immunology; D007249:Inflammation / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000502:physiology*; D050378:T-Lymphocytes, Regulatory / Q000502:physiology*; D058504:Th17 Cells / Q000502:physiology*