title: Origin of IgM(+)IgG(+) lymphocytes in the bursa of Fabricius.
abstract: IgM(+)IgG(+) B cells were detected, by immunofluorescence staining of single cells, in the bursa of Fabricius after hatching. To study the role of maternal IgG (MIgG) in this emergence of IgM(+)IgG(+) B cells, MIgG-free chicks were established from surgically bursectomized hens. Deprivation of MIgG in chicks completely prevented the appearance of IgM(+)IgG(+) B cells in the bursa 1 week after hatching. However, introduction of fluorescein-isothiocyanate-labeled MIgG to MIgG-free chick embryos on day 18 of incubation retrieved IgM(+)IgG(+) B cells in the bursa 1 week after hatching. Thus, IgM(+)IgG(+) B cells are induced by the binding of MIgG to IgM(+) B cells in the bursa after hatching. Nevertheless, no binding of MIgG to IgM(+) B cells was observed in the bursa of chick embryos in which B-cell proliferation and differentiation were independent of external antigens (Ags). Additionally, the binding of MIgG to IgM(+) B cells after hatching was prevented by the isolation of the bursa from environmental stimuli by bursal duct ligation. Therefore, Ag stimulation from the external environment to the bursa is indispensable for the binding of MIgG to IgM(+) B cells in the bursa. Taken together, the data demonstrate that IgM(+)IgG(+) B cells are generated by Ag-dependent binding of MIgG to IgM(+) B cells in the bursa after hatching.
authors.affiliation: Department of Histology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto, Japan. 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
authors.affiliation: Department of Immunology and Hematology, School of Health Sciences, Kumamoto University, Kuhonji, Kumamoto, Japan. inui@kumamoto-u.ac.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Inui
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism*; D002060:Bursa of Fabricius / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation; D002642:Chick Embryo; D007074:Immunoglobulin G / Q000276:immunology*; D007075:Immunoglobulin M / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D007075:Immunoglobulin M
keywords: Bursa of Fabricius; Chick; Complement; IgM+IgG+ B cells; Immune complex; Maternal IgG