title: The role of IL-5 for mature B-1 cells in homeostatic proliferation, cell survival, and Ig production.
abstract: B-1 cells, distinguishable from conventional B-2 cells by their cell surface marker, anatomical location, and self-replenishing activity, play an important role in innate immune responses. B-1 cells constitutively express the IL-5R alpha-chain (IL-5Ralpha) and give rise to Ab-producing cells in response to various stimuli, including IL-5 and LPS. Here we report that the IL-5/IL-5R system plays an important role in maintaining the number and the cell size as well as the functions of mature B-1 cells. The administration of anti-IL-5 mAb into wild-type mice, T cell-depleted mice, or mast cell-depleted mice resulted in reduction in the total number and cell size of B-1 cells to an extent similar to that of IL-5Ralpha-deficient (IL-5Ralpha(-/-)) mice. Cell transfer experiments have demonstrated that B-1 cell survival in wild-type mice and homeostatic proliferation in recombination-activating gene 2-deficient mice are impaired in the absence of IL-5Ralpha. IL-5 stimulation of wild-type B-1 cells, but not IL-5Ralpha(-/-) B-1 cells, enhances CD40 expression and augments IgM and IgG production after stimulation with anti-CD40 mAb. Enhanced IgA production in feces induced by the oral administration of LPS was not observed in IL-5Ralpha(-/-) mice. Our results illuminate the role of IL-5 in the homeostatic proliferation and survival of mature B-1 cells and in IgA production in the mucosal tissues.
authors.affiliation: Division of Immunology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors.forename: Byoung-gon
authors.initials: BG
authors.lastname: Moon
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takaki
authors.forename: Kensuke
authors.initials: K
authors.lastname: Miyake
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takatsu
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D019013:CD40 Antigens / Q000096:biosynthesis / Q000276:immunology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D048429:Cell Size / Q000235:genetics / Q000276:immunology; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D006706:Homeostasis / Q000235:genetics / Q000276:immunology*; D017098:IgA Deficiency / Q000235:genetics / Q000276:immunology; D007136:Immunoglobulins / Q000096:biosynthesis*; D007274:Injections, Intraperitoneal; D015848:Interleukin-5 / Q000096:biosynthesis / Q000276:immunology / Q000502:physiology*; D008070:Lipopolysaccharides / Q000008:administration & dosage; D008231:Lymphopenia / Q000276:immunology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D018123:Receptors, Interleukin / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D053649:Receptors, Interleukin-5; D013601:T-Lymphocytes / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D019013:CD40 Antigens; D007136:Immunoglobulins; D015848:Interleukin-5; D008070:Lipopolysaccharides; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5