title: TCR-independent proliferation and differentiation of human CD4+ T cell subsets induced by cytokines.
abstract: Naïve and memory T cells can divide in an antigen-independent manner in vivo maintaining independently a constant pool size. While naïve T cells require TCR tickling by self-MHC for homeostatic proliferation in lymphopenic mice, memory cells do not but respond to cytokines. Human naive and memory CD4+ T cell subsets can be selectively expanded in vitro with different cytokine combinations. Responsiveness of T cells to homeostatic cytokines is associated with the differentiation state. Thus, while memory cells respond directly to IL-7 and IL-15, naïve T cells require costimulation by dendritic cell-derived cytokines, and selectively respond to IL-4. This differential cytokine responsiveness is associated with the expression and modulation of the relevant cytokine receptors. Cytokine-driven proliferation is independent of TCR-stimulation and shows distinct signal transduction requirements. While cytokine-expanded naive T cells maintain a naive phenotype, memory cells differentiate acquiring new effector functions and switching expression of chemokine receptors. Thus human naïve and memory T cell pools can be maintained with homeostatic cytokines in the absence of TCR stimulation.
authors.affiliation: Institute for Research in Biomedicine, Bellinzona, Switzerland.
authors.forename: Jens
authors.initials: J
authors.lastname: Geginat
authors.forename: Stefania
authors.initials: S
authors.lastname: Campagnaro
authors.forename: Federica
authors.initials: F
authors.lastname: Sallusto
authors.forename: Antonio
authors.initials: A
authors.lastname: Lanzavecchia
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation; D016207:Cytokines / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D008213:Lymphocyte Activation / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D016207:Cytokines; D011948:Receptors, Antigen, T-Cell