title: The changing preference of T and B cells for partners as T-dependent antibody responses develop.
abstract: Recirculating virgin CD4+ T cells spend their life migrating between the T zones of secondary lymphoid tissues where they screen the surface of interdigitating dendritic cells. T-cell priming starts when processed peptides or superantigen associated with class II MHC molecules are recognised. Those primed T cells that remain within the lymphoid tissue move to the outer T zone, where they interact with B cells that have taken up and processed antigen. Cognate interaction between these cells initiates immunoglobulin (Ig) class switch-recombination and proliferation of both B and T cells; much of this growth occurs outside the T zones B cells migrate to follicles, where they form germinal centres, and to extrafollicular sites of B-cell growth, where they differentiate into mainly short-lived plasma cells. T cells do not move to the extrafollicular foci, but to the follicles; there they proliferate and are subsequently involved in the selection of B cells that have mutated their Ig variable-region genes. During primary antibody responses T-cell proliferation in follicles produces many times the peak number of T cells found in that site: a substantial proportion of the CD4+ memory T-cell pool may originate from growth in follicles.
authors.affiliation: Department of Immunology, University of Birmingham Medical School, United Kingdom. i.c.m.maclennan@bham.ac.uk
authors.forename: I C
authors.initials: IC
authors.lastname: MacLennan
authors.forename: A
authors.initials: A
authors.lastname: Gulbranson-Judge
authors.forename: K M
authors.initials: KM
authors.lastname: Toellner
authors.forename: M
authors.initials: M
authors.lastname: Casamayor-Palleja
authors.forename: E
authors.initials: E
authors.lastname: Chan
authors.forename: D M
authors.initials: DM
authors.lastname: Sze
authors.forename: S A
authors.initials: SA
authors.lastname: Luther
authors.forename: H A
authors.initials: HA
authors.lastname: Orbea
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002465:Cell Movement; D003713:Dendritic Cells / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D011947:Receptors, Antigen, B-Cell