title: Follicular associated T cells and their B-cell helper qualities.
abstract: The immune system utilizes sophisticated cellular surveillance mechanisms to maintain the integrity of the multicellular host. Adaptive immunosurveillance in particular constitutes a powerful branch of the immune system that houses the capacity to mount exquisitely specific responses against a diverse array of foreign antigens. Central to the development of adaptive immunity is the activation of T and B cells. Upon antigen engagement, T and B cells have been observed to undergo striking changes in their migratory status and distribution within secondary lymphoid organs, a phenomenon that is to a large extent controlled through their altered responsiveness to homeostatic T- and B-zone chemokines. Changes in their chemokine receptor expression and/or sensitivity to their respective ligands assist in bringing rare antigen-specific T and B lymphocytes, dendritic cells and CD4+CD3(-) accessory cells together. Cognate interaction between these cells at the T-B junction can support the generation of extrafollicular foci of antibody producing plasma cells and the formation of germinal centers. Such T-dependent antibody responses are highly dependent on the functional properties and activity of a specialized subset of CXCR5+ICOS+ CD4 T cells referred to as T follicular helper cells (T FH). This review presents an overview of some of the defining characteristics of this subset of T-helper cells and the chemokine receptors and their ligands that help dictate the migratory activity of T(FH) cells within secondary lymphoid organs.
authors.affiliation: Research Division, Peter MacCallum Cancer Institute, Melbourne, Victoria, Australia. Nicole.Haynes@petermac.org
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Haynes
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology; D015704:CD4 Antigens / Q000032:analysis; D018925:Chemokines / Q000378:metabolism; D018858:Germinal Center / Q000276:immunology*; D006801:Humans; D060889:Inducible T-Cell Co-Stimulator Protein; D008213:Lymphocyte Activation; D051379:Mice; D054380:Receptors, CXCR5 / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D015704:CD4 Antigens; D018925:Chemokines; C556692:ICOS protein, human; C556694:Icos protein, mouse; D060889:Inducible T-Cell Co-Stimulator Protein; D054380:Receptors, CXCR5