title: CD79 alpha/CD79 beta heterodimers are expressed on pro-B cell surfaces without associated mu heavy chain.
abstract: During B cell development, the surface expression of CD79 alpha/CD79 beta heterodimers had been thought to begin in the pre-B cell stage where the heterodimers constitute pre-B cell receptors together with mu heavy and surrogate light chains. Thereafter, in mature B cells, CD79 alpha/CD79 beta associates with surface Ig to form B cell antigen receptors. In this study, we revealed by using newly established mAb that CD79 beta was expressed on the surface of pro-B cells which had not undergone the productive Ig gene rearrangement. Biochemical analysis showed that CD79 beta on pro-B cells existed either as monomers or as disulfide-linked heterodimers with CD79 alpha, non-covalently associated with four unidentified membrane molecules. Our finding that CD79 beta is expressed on earlier B-lineage cells than previously expected coincides with the recent study in which CD79 beta-deficient mice exhibit a blockade of B cell differentiation at the pro-B cell stage. Thus, it is speculated that the CD79 beta-containing complexes on pro-B cell surfaces may function to induce early B cell differentiation.
authors.affiliation: Department of Infectious Diseases and Applied Immunology, University of Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Koyama
authors.forename: K
authors.initials: K
authors.lastname: Ishihara
authors.forename: H
authors.initials: H
authors.lastname: Karasuyama
authors.forename: J L
authors.initials: JL
authors.lastname: Cordell
authors.forename: A
authors.initials: A
authors.lastname: Iwamoto
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D051925:CD79 Antigens; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D019281:Dimerization; D000939:Epitopes / Q000032:analysis; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis* / Q000378:metabolism; D007148:Immunoglobulin mu-Chains / Q000096:biosynthesis* / Q000378:metabolism; D051379:Mice; D011947:Receptors, Antigen, B-Cell / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D051925:CD79 Antigens; C497882:Cd79a protein, mouse; D000939:Epitopes; D007143:Immunoglobulin Heavy Chains; D007148:Immunoglobulin mu-Chains; D011947:Receptors, Antigen, B-Cell