title: Heterogeneity of immunoglobulin-associated molecules on human B cells identified by monoclonal antibodies.
abstract: Two covalently linked transmembrane molecules, encoded in mice by the mb-1 and B29 genes, have been defined as integral components of the antibody receptor units expressed on B cells. We have produced monoclonal antibodies against an exposed extracellular epitope on the putative human equivalent of the mouse B29 product. These antibodies, CB3-1 and -2, were used to show that cytoplasmic expression of this molecule begins in human pro-B cells (terminal deoxynucleotidyltransferase-positive, mu chain-negative), whereas surface expression coincides strictly with surface immunoglobulin expression of all isotypes. Immunochemical analysis of the human immunoglobulin-associated molecules revealed greater molecular heterogeneity than has been noted for the murine analogues. This molecular heterogeneity of immunoglobulin-associated molecules varied as a function of differentiation stage and the immunoglobulin isotypes expressed by B-lineage cells. Our data support the hypothesis that biochemical heterogeneity of the surface immunoglobulin-associated molecules may contribute to the variability in biological effects of antigen receptor crosslinkage on B cells of different maturational stages. Because the CB3 antibodies are capable of down-modulating the antigen receptors on all B cells, they may prove therapeutically useful as universal B-cell suppressants.
authors.affiliation: Department of Medicine, University of Alabama, Birmingham.
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Kubagawa
authors.forename: M D
authors.initials: MD
authors.lastname: Cooper
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000954:Antigens, Surface / Q000737:chemistry*; D001402:B-Lymphocytes / Q000737:chemistry* / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D003593:Cytoplasm / Q000276:immunology; D015536:Down-Regulation; D000939:Epitopes; D006801:Humans; D046911:Macromolecular Substances; D011947:Receptors, Antigen, B-Cell / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D000939:Epitopes; D046911:Macromolecular Substances; D011947:Receptors, Antigen, B-Cell