title: New insight into the origin of IgG-bearing cells in the bursa of Fabricius.
abstract: The bursa of Fabricius is a primary lymphoid organ for B-cell development and gut-associated lymphoid tissue. After hatching, IgG-containing cells with reticular branches are found in the medulla of bursal follicles on frozen sections stained with anti-Cγ antibody, and IgM(+)IgG(+) B cells are detected in single-cell suspension of the bursa. IgG-containing cells in the medulla do not biosynthesize IgG and are composed of aggregated maternal IgG and environmental antigens. Then, those cells in the medulla are acknowledged as follicular dendritic cells retaining immune complexes. Also, it is presumed that IgM(+)IgG(+) B cells are generated by the attachment of immune complexes to IgM(+) bursal B cells because IgM(+)IgG(+) B cells are induced by antigen-dependent attachment of maternal IgG. Therefore, it is reasonable to suppose that immune complexes exert further B-cell differentiation in the medulla.
authors.affiliation: Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto, Japan. Electronic address: ekino@gpo.kumamoto-u.ac.jp.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ekino
authors.affiliation: Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Sonoda
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D002060:Bursa of Fabricius / Q000166:cytology* / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology*; D002645:Chickens; D007074:Immunoglobulin G / Q000276:immunology*; D007075:Immunoglobulin M / Q000276:immunology
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M
keywords: Bursa of Fabricius; Environmental antigens; Follicular dendritic cells; IgG-containing cells; IgM(+)IgG(+) double-positive cells; Immune complexes; Maternal IgG; Somatic mutation