Th9 cells, new players in adaptive immunity.
Upon antigen-specific stimulation, naïve CD4⁺ T cells have the potential to differentiate into various T helper (Th) cell subsets. Earlier models of Th cell differentiation focused on IFN-γ-producing Th1 cells and IL-4-secreting Th2 cells. The discovery of additional CD4⁺ Th cell subsets has extended our understanding of Th cell differentiation beyond this dichotomy. Among these is the recently described Th9 cell subset, which preferentially produces interleukin (IL)-9. Here, we review the latest developments in Th9 cell development and differentiation, focusing on contributing environmental signals, and discuss potential physiological and pathophysiological functions of these cells. We describe the challenges inherent to unambiguously defining roles for Th9 cells using the available experimental animal models, and suggest new experimental models to address these concerns.
Institute for Immunology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, Building 708, 55131 Mainz, Germany.
Edgar
E
Schmitt
Institute for Immunology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, Building 708, 55131 Mainz, Germany.
Matthias
M
Klein
Institute for Immunology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, Building 708, 55131 Mainz, Germany. Electronic address: boppt@uni-mainz.de.
Tobias
T
Bopp
D056704:Adaptive Immunity; D000818:Animals; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D050835:Interferon Regulatory Factors / Q000235:genetics / Q000378:metabolism; D016906:Interleukin-9 / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D018448:Models, Immunological; D009369:Neoplasms / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D019948:Receptors, Interleukin-4 / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000145:classification / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000145:classification / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D000099218:Interferon Regulatory Factor-4
D050835:Interferon Regulatory Factors; D016906:Interleukin-9; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2; D019948:Receptors, Interleukin-4; D016212:Transforming Growth Factor beta; D000099218:Interferon Regulatory Factor-4
T helper cell; Th9; cytokine; interleukin-9; lymphocyte differentiation; plasticity; transcription factor