title: Cutting edge: induction of follicular homing precedes effector Th cell development.
abstract: Transition from naive to Ag-experienced effector/memory CD4+ T cells is initiated during contact with APC in secondary lymphoid tissue. Here, we demonstrate that the CXCR5 is a marker for recently activated memory CD4+ T cells. CXCR5 is rapidly induced during contact with Ag-presenting dendritic cells, well before T cell expansion and effector cell development, and is irreversibly lost on terminally differentiated effector cells. Furthermore, immunization of human volunteers with a recall Ag results in rapid accumulation of Ag-responsive, CXCR5-expressing CD4+ T cells in peripheral blood. Early acquisition of a new migration program enables T zone CD4+ T cells to develop into follicular B helper T cells or, alternatively, into circulating memory CD4+ T cells. Together, CXCR5 unequivocally defines pre-effector memory CD4+ T cells generated during ongoing immune responses.
authors.affiliation: Theodor-Kocher Institute, University of Bern, Bern, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Schaerli
authors.forename: P
authors.initials: P
authors.lastname: Loetscher
authors.forename: B
authors.initials: B
authors.lastname: Moser
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology; D002465:Cell Movement / Q000276:immunology*; D002478:Cells, Cultured; D019743:Chemokines, CXC / Q000378:metabolism*; D006801:Humans; D007114:Immunization; D007156:Immunologic Memory; D007399:Interphase / Q000276:immunology; D008213:Lymphocyte Activation; D054380:Receptors, CXCR5; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine / Q000096:biosynthesis* / Q000097:blood; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D013745:Tetanus Toxoid / Q000276:immunology
chemical_list: C095085:CXCR5 protein, human; D019743:Chemokines, CXC; D054380:Receptors, CXCR5; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine; D013745:Tetanus Toxoid