title: B1b lymphocyte-derived antibodies control Borrelia hermsii independent of Fcα/μ receptor and in the absence of host cell contact.
abstract: The critical role of IgM in controlling pathogen burden has been demonstrated in a variety of infection models. In the murine model of Borrelia hermsii infection, IgM is necessary and sufficient for the rapid clearance of bacteremia. Convalescent, but not naïve, B1b cells generate a specific IgM response against B. hermsii, but the mechanism of IgM-mediated protection is unknown. Here, we show that neither Fcα/μR, a high-affinity receptor for IgM, nor IgM-dependent complement activation is required for controlling B. hermsii. Bacteria in diffusion chambers with a pore size impermeable to cells were killed when diffusion chambers were implanted into either convalescent or passively immunized mice. Furthermore, adoptively transferred convalescent B1b cells in Rag1(-/-) mice produced specific IgM that also cleared B. hermsii in diffusion chambers independent of complement. These results demonstrate that IgM-mediated clearance of B. hermsii does not require opsonophagocytosis and indicate that a mechanism for in vivo B1b cell-mediated protection is through the generation of bactericidal IgM.
authors.affiliation: Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, 233 S 10th Street, Room 726, Philadelphia, PA 19107, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Colombo
authors.forename: David
authors.initials: D
authors.lastname: Abraham
authors.forename: Akira
authors.initials: A
authors.lastname: Shibuya
authors.forename: Kishore R
authors.initials: KR
authors.lastname: Alugupalli
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D000920:Antibody-Dependent Cell Cytotoxicity; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000637:transplantation; D001898:Borrelia / Q000276:immunology* / Q000472:pathogenicity; D001899:Borrelia Infections / Q000235:genetics / Q000276:immunology*; D002478:Cells, Cultured; D003176:Complement C3 / Q000235:genetics / Q000276:immunology; D054884:Host-Pathogen Interactions; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology*; D051379:Mice; D010587:Phagocytosis; D011961:Receptors, Fc / Q000276:immunology; D058248:Serum Bactericidal Antibody Assay
chemical_list: D000907:Antibodies, Bacterial; D003176:Complement C3; D007075:Immunoglobulin M; D011961:Receptors, Fc