title: Differentially regulated expression and function of CD22 in activated B-1 and B-2 lymphocytes.
abstract: CD22 is a B cell-restricted transmembrane protein that apparently controls signal transduction thresholds initiated through the B cell Ag receptor (BCR) in response to Ag. However, it is still poorly understood how the expression of CD22 is regulated in B cells after their activation. Here we show that the expression levels of CD22 in conventional B-2 cells are markedly down-regulated after cross-linking of BCR with anti-IgM mAb but are up-regulated after stimulation with LPS, anti-CD40 mAb, or IL-4. In contrast, treatment with anti-IgM mAb barely modulated the expression levels of CD22 in CD5(+) B-1 cells, consistent with a weak Ca(2+) response in anti-IgM-treated CD5(+) B-1 cells. Moreover, in CD22-deficient mice, anti-IgM treatment did not trigger enhanced Ca(2+) influx in CD5(+) B-1 cells, unlike CD22-deficient splenic B-2 cells, suggesting a relatively limited role of CD22 in BCR signaling in B-1 cells. In contrast, CD22 levels were markedly down-regulated on wild-type B-1 cells in response to LPS or unmethylated CpG-containing oligodeoxynucleotides. These data indicate that the expression and function of CD22 are differentially regulated in B-1 and conventional B-2 cells, which are apparently implicated in innate and adaptive immunity, respectively.
authors.affiliation: Department of Pathology, University of Geneva, Geneva, Switzerland.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lajaunias
authors.forename: Lars
authors.initials: L
authors.lastname: Nitschke
authors.forename: Thomas
authors.initials: T
authors.lastname: Moll
authors.forename: Eduardo
authors.initials: E
authors.lastname: Martinez-Soria
authors.forename: Isabelle
authors.initials: I
authors.lastname: Semac
authors.forename: Yves
authors.initials: Y
authors.lastname: Chicheportiche
authors.forename: R Michael E
authors.initials: RM
authors.lastname: Parkhouse
authors.forename: Shozo
authors.initials: S
authors.lastname: Izui
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000096:biosynthesis* / Q000378:metabolism / Q000502:physiology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000096:biosynthesis* / Q000378:metabolism / Q000502:physiology; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism*; D019013:CD40 Antigens / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000276:immunology; D015815:Cell Adhesion Molecules; D002478:Cells, Cultured; D018899:CpG Islands / Q000276:immunology; D015536:Down-Regulation / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D015847:Interleukin-4 / Q000494:pharmacology; D037102:Lectins; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D010537:Peritoneum / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051918:Sialic Acid Binding Ig-like Lectin 2; D013154:Spleen / Q000166:cytology / Q000276:immunology; D015854:Up-Regulation / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D019013:CD40 Antigens; C408982:CPG-oligonucleotide; C497868:Cd22 protein, mouse; D015815:Cell Adhesion Molecules; D007075:Immunoglobulin M; D037102:Lectins; D008070:Lipopolysaccharides; D009838:Oligodeoxyribonucleotides; D051918:Sialic Acid Binding Ig-like Lectin 2; C044203:anti-IgM; D015847:Interleukin-4; D002118:Calcium