The effect of alpha2,6-linked sialic acid on anti-IgM antibody-induced apoptosis in Ramos cells.
Apoptosis in B cells is induced through the B cell antigen receptor (BCR) and affects the sialic acid recognition molecules on B cells. We investigated the effects of alpha(1)-acid glycoprotein (AGP), which mainly contains alpha2,6-linked sialic acid, on anti-IgM antibody (Ab)-induced apoptosis in Ramos cells, which are derived from Burkitt's lymphoma. When Ramos cells were incubated with anti-IgM-Ab in plates coated with AGP, neuraminidase-digested AGP (asAGP) or alpha2,3-sialylated AGP (2,3AGP), apoptosis was suppressed only in those coated with AGP. We also studied the effects of CD22, which is expressed on the surface of mature B cells and binds to sugar chains containing alpha2,6-linked sialic acid, with anti-CD22 monoclonal antibody (mAb). Anti-CD22mAb enhanced anti-IgM Ab-induced apoptosis in Ramos cells. These contradictory results suggested that the recognition molecules for alpha2,6-linked sialic acid on AGP, which inhibits B-cell apoptosis, is distinct from CD22, or that different binding domains of CD22 between alpha2,6-linked sialic acid and anti-CD22 mAb exert opposite functions of suppression or enhancement to anti-IgM Ab-induced B cells.
Azuma
Y
Y
Department of Clinical Chemistry, School of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan. yutaro@phar.toho-u.ac.jp
Sakanashi
M
M
Matsumoto
K
K
D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D001402:B-Lymphocytes / Q000166:cytology* / Q000187:drug effects* / Q000276:immunology; D002236:Carbohydrate Conformation; D015815:Cell Adhesion Molecules; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D005434:Flow Cytometry; D006801:Humans; D037102:Lectins; D019158:N-Acetylneuraminic Acid / Q000737:chemistry* / Q000494:pharmacology*; D009961:Orosomucoid / Q000737:chemistry / Q000494:pharmacology*; D051918:Sialic Acid Binding Ig-like Lectin 2; D014407:Tumor Cells, Cultured
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; C497867:CD22 protein, human; D015815:Cell Adhesion Molecules; D037102:Lectins; D009961:Orosomucoid; D051918:Sialic Acid Binding Ig-like Lectin 2; C044203:anti-IgM; D019158:N-Acetylneuraminic Acid