title: B-1a cell origin of the murine B lymphoma line BCL1 characterized by surface markers and bacterial reactivity of its surface IgM.
abstract: B cells are divided into two categories: conventional or B-2B cells and B-1B cells, the latter of which are distinguished by their different ontogeny. B cell lymphoma 1 (BCL1), the first-reported case of a spontaneously developed mouse B-lymphoma, expresses CD5, surface IgM, Mac-1, CD43 and low level of B220, and is likely to have B-1a cell origin. However, antigens recognized by IgM produced by the BCL1 cells (BCL1-IgM) have not been identified. Here, we demonstrate that BCL1-IgM reacts with Escherichia coli (E. coli). Our initial finding that several recombinant proteins expressed in E. coli bound to BCL1-B20 prompted us to examine the possibility that BCL1 cells may bind E. coli. Indeed, BCL1 cells bound fluorescein-labeled E. coli. To elucidate the structure on the BCL1 cells responsible for E. coli-binding, we produced a monoclonal antibody capable of inhibiting BCL1 binding to E. coli. The antibody recognizes an idiotypic epitope on the BCL1-IgM. Moreover, polyclonal antibody against IgM and secreted BCL1-IgM purified from the supernatants inhibited BCL1 binding to E. coli. Finally, transfection of non-lymphoid cells with cDNA of heavy and light chains of BCL1-IgM conferred the cells ability to bind E. coli. These results clearly indicate that BCL1-IgM bind E. coli and suggest that BCL1 lymphoma is a typical B-1 cell-derived lymphoma, characterized not only by the surface phenotype, but also by the reactivity of its IgM with commensal bacteria.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Bioscience Building, Suite 602, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Koganei
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ito
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology; D000943:Antigens, Differentiation / Q000032:analysis*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology / Q000473:pathology*; D001483:Base Sequence; D045744:Cell Line, Tumor; D019070:Cell Lineage; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D004926:Escherichia coli / Q000276:immunology; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology; D007147:Immunoglobulin Light Chains / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology*; D016130:Immunophenotyping; D051379:Mice; D008969:Molecular Sequence Data; D010641:Phenotype; D051381:Rats; D016415:Sequence Alignment
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D018985:Epitopes, B-Lymphocyte; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007075:Immunoglobulin M