title: Plasticity of human CD4 T cell subsets.
abstract: Human beings are exposed to a variety of different pathogens, which induce tailored immune responses and consequently generate highly diverse populations of pathogen-specific T cells. CD4(+) T cells have a central role in adaptive immunity, since they provide essential help for both cytotoxic T cell- and antibody-mediated responses. In addition, CD4(+) regulatory T cells are required to maintain self-tolerance and to inhibit immune responses that could damage the host. Initially, two subsets of CD4(+) helper T cells were identified that secrete characteristic effector cytokines and mediate responses against different types of pathogens, i.e., IFN-γ secreting Th1 cells that fight intracellular pathogens, and IL-4 producing Th2 cells that target extracellular parasites. It is now well established that this dichotomy is insufficient to describe the complexity of CD4(+) T cell differentiation, and in particular the human CD4 compartment contains a myriad of T cell subsets with characteristic capacities to produce cytokines and to home to involved tissues. Moreover, it has become increasingly clear that these T cell subsets are not all terminally differentiated cells, but that the majority is plastic and that in particular central memory T cells can acquire different properties and functions in secondary immune responses. In addition, there is compelling evidence that helper T cells can acquire regulatory functions upon chronic stimulation in inflamed tissues. The plasticity of antigen-experienced human T cell subsets is highly relevant for translational medicine, since it opens new perspectives for immune-modulatory therapies for chronic infections, autoimmune diseases, and cancer.
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Jens
authors.initials: J
authors.lastname: Geginat
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Moira
authors.initials: M
authors.lastname: Paroni
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Maglie
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Johanna Sophie
authors.initials: JS
authors.lastname: Alfen
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Ilko
authors.initials: I
authors.lastname: Kastirr
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Gruarin
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: De Simone
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Pagani
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi" INGM , Milan , Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Abrignani
keywords: CD4 T cells; cytokines; differentiation; plasticity; tissue homing