title: The IgM-associated protein mb-1 as a marker of normal and neoplastic B cells.
abstract: Recent evidence indicates that the transmembrane form of IgM on murine and human B lymphocytes is physically associated with at least two proteins, forming a disulfide-linked dimer, which may control cell surface expression of IgM and also play a role in signal transduction after Ag binding (by analogy with the TCR-associated CD3 components in T lymphocytes). We have used mAb and polyclonal antibodies against an intracytoplasmic epitope on one of these polypeptides (previously identified in murine B cells as the product of the B cell specific mb-1 gene) to study the distribution of the IgM-associated dimer in human cells. By immunocytochemical staining of normal and neoplastic B cells, we show that the human mb-1 protein appears early in B cell differentiation, probably before expression of cytoplasmic mu-chain, and persists until the plasma cell stage, where it is seen as an intracytoplasmic component. According to immunohistologic analysis of reactive lymphoid tissue and lymphoma samples, mb-1 protein is completely B cell specific. Anti-mb-1 also labels B cell areas in tissues from seven different mammalian species. Finally, the Ig-associated dimer could be isolated from human hairy-cell leukemia cells in high purity and yield by affinity chromatography using anti-mb-1 antibody. Mice immunized with this material have produced a strong polyclonal response, so that it should now be possible to prepare a panel of new mAb reactive with different epitopes on both mb-1 and on its associated polypeptide(s).
authors.affiliation: Department of Haematology, John Radcliffe Hospital, Headington, Oxford, U.K.
authors.forename: D Y
authors.initials: DY
authors.lastname: Mason
authors.forename: J L
authors.initials: JL
authors.lastname: Cordell
authors.forename: A G
authors.initials: AG
authors.lastname: Tse
authors.forename: J J
authors.initials: JJ
authors.lastname: van Dongen
authors.forename: C J
authors.initials: CJ
authors.lastname: van Noesel
authors.forename: K
authors.initials: K
authors.lastname: Micklem
authors.forename: K A
authors.initials: KA
authors.lastname: Pulford
authors.forename: F
authors.initials: F
authors.lastname: Valensi
authors.forename: W M
authors.initials: WM
authors.lastname: Comans-Bitter
authors.forename: J
authors.initials: J
authors.lastname: Borst
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte / Q000737:chemistry* / Q000378:metabolism; D001402:B-Lymphocytes / Q000502:physiology*; D015415:Biomarkers; D014408:Biomarkers, Tumor; D015153:Blotting, Western; D001854:Bone Marrow Cells; D051925:CD79 Antigens; D002454:Cell Differentiation; D002846:Chromatography, Affinity; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007075:Immunoglobulin M / Q000378:metabolism*; D008223:Lymphoma / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D011233:Precipitin Tests; D011947:Receptors, Antigen, B-Cell; D013045:Species Specificity
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D015415:Biomarkers; D014408:Biomarkers, Tumor; D051925:CD79 Antigens; C497881:CD79A protein, human; D007075:Immunoglobulin M; D008562:Membrane Glycoproteins; D011947:Receptors, Antigen, B-Cell