title: Essential role of antigen-presenting cell-derived BAFF for antibody responses.
abstract: Antigen-presenting cells (APC) are directly involved in survival, growth and differentiation of naive B cells and in immunoglobulin class switch recombination. Less is known about the contribution of APC to memory B cell responses. We employed an in vitro model to investigate the secondary humoral response against foot-and-mouth disease virus, with cells from a natural host of the virus - the pig. This response is T cell-dependent. Under conditions of limited T cell help, defined as a low T-to-B cell ratio or by the replacement of T cells with interleukin-2 only, the antibody response was dependent on APC. These included monocytes and monocyte-derived DC, but not plasmacytoid DC. APC mediated their help through soluble factors, particularly soluble B cell-activating factor belonging to the TNF family (BAFF). Our results suggest that the 'ménage à trois' concept, saying that both APC and T cells have a direct effect in B cell activation, is also valid for secondary B cell responses, and imply an important role for BAFF under conditions that might be physiologically relevant in secondary lymphoid organs.
authors.affiliation: Institute of Virology and Immunoprophylaxis, Mittelhäusern, Switzerland.
authors.forename: Fabio
authors.initials: F
authors.lastname: Bergamin
authors.forename: Isabelle E
authors.initials: IE
authors.lastname: Vincent
authors.forename: Artur
authors.initials: A
authors.lastname: Summerfield
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: McCullough
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000938:Antigen-Presenting Cells / Q000276:immunology*; D053264:B-Cell Activating Factor / Q000276:immunology* / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology; D005434:Flow Cytometry; D029544:Foot-and-Mouth Disease Virus / Q000276:immunology; D007156:Immunologic Memory; D008213:Lymphocyte Activation / Q000276:immunology; D013552:Swine; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D053264:B-Cell Activating Factor