Signal transduction in human B cells initiated via Ig{beta} ligation |
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Authors: | Nakamura, Tetsuya Sekar, M. Chandra Kubagawa, Hiromi Cooper, Max D. |
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Affiliation: | Division of Developmental and Clinical Immunology, Departments of Medicine, Pathology, Pediatrics, and Microbiology, University of Alabama at Birmingham, and the Howard Hughes Medical Institute Birmingham, AL 35294, USA 1Present address: First Department of Internal Medicine, Faculty of Medicine, University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan |
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Abstract: | Ig and Igß heterodimers are non-covalently associatedwith Ig to compose the antigen receptor complexes on B cells.The demonstration that different sets of tyrosine kinases bindto the cytoplasmic tails of Ig and Igß suggests thatIg and Igß may activate distinct second messengerpathways. In this study, we examined the effects of mAbs againstan exposed epitope of human Igß on pre-B and B celltriggering. Cross-linkage of Igß on B cells leadsto activation of tyrosine kinases, hydrolysis of phosphatidylinositides,and elevation of intracellular Ca2+, effects qualitatively identicalto those of anti-µ mAbs. Our observations thus indicatethat cross-linking of Igß does not segregate signaltransduction pathways connected with the cytoplasmic talls ofIg and Igß. Ig ligation has been reported to be moreeffective in triggering pre-B than B cells, whereas our resultsindicated that Igß ligation is more efficient in triggeringB than pre-B cells. In addition to their activation properties,the anti-Igß mAbs effectively modulated B cell receptorcomplexes and blocked terminal differentiation of all plasmacell isotypes. The findings support the idea that anti-Igßcould serve as a universal B cell immunosuppressant. |
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Keywords: | B cell activation Ig /math/alpha.gif" ALT=" {alpha}" BORDER=" 0" > mb-1 surface Ig |
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