title: Cutting edge: selection of B lymphocyte subsets is regulated by natural IgM.
abstract: Natural IgM has a wide range of actions in the immune system. Here we demonstrate that mice lacking serum IgM have an expansion in splenic marginal zone B cells with a proportionately smaller reduction in follicular B cells. The increase in the marginal zone-follicular B cell ratio (and an expansion in peritoneal B1a cells) is fully reversed by administration of polyclonal IgM, but not by two IgM monoclonals. Mice engineered to have a secreted oligoclonal IgM repertoire with an endogenous membrane IgM also exhibited a similar expansion of marginal zone B cells. We propose that natural IgM, by virtue of its polyreactivity, enhances Ag-driven signaling through the B cell receptor and promotes the formation of follicular B cells. These results demonstrate that natural IgM regulates the selection of B lymphocyte subsets.
authors.affiliation: Department of Medicine, University College London, London, United Kingdom.
authors.forename: Nicole
authors.initials: N
authors.lastname: Baker
authors.forename: Michael R
authors.initials: MR
authors.lastname: Ehrenstein
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D000937:Antigen-Antibody Reactions; D016175:B-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D002999:Clone Cells; D003433:Crosses, Genetic; D006131:Growth Inhibitors / Q000235:genetics / Q000502:physiology; D007106:Immune Sera / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D007075:Immunoglobulin M / Q000097:blood / Q000172:deficiency / Q000378:metabolism / Q000502:physiology*; D018655:Lymphocyte Count; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D013154:Spleen / Q000166:cytology / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D006131:Growth Inhibitors; D007106:Immune Sera; D007075:Immunoglobulin M