CD79 alpha/CD79 beta heterodimers are expressed on pro-B cell surfaces without associated mu heavy chain.
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.
Koyama
M
M
Department of Infectious Diseases and Applied Immunology, University of Tokyo, Japan.
Ishihara
K
K
Karasuyama
H
H
Cordell
J L
JL
Iwamoto
A
A
Nakamura
T
T
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
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