title: Mouse IgM Fc receptor, FCMR, promotes B cell development and modulates antigen-driven immune responses.
abstract: FcR specific for pentameric IgM (FCMR) is expressed at high levels by B cells. Although circulating IgM has profound effects on responses to pathogens, autoimmunity, and B cell homeostasis, the biologic consequences of its binding to FCMR are poorly understood. We interrogated FCMR contributions to B cell function by studying mice that lack FCMR. FCMR transcripts are expressed at different levels by various B cell subsets. FCMR-deficient mice have reduced numbers of developing B cells, splenic follicular and peritoneal B-2 cells, but increased levels of peritoneal B-1a cells and autoantibodies. After immunization, germinal center B cell and plasma cell numbers are increased. FCMR-deficient B cells are sensitive to apoptosis induced by BCR ligation. Our studies demonstrate that FCMR is required for B cell differentiation and homeostasis, the prevention of autoreactive B cells, and responsiveness to antigenic challenge.
authors.affiliation: Receptor Cell Biology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
authors.forename: Seung-Chul
authors.initials: SC
authors.lastname: Choi
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Wang
authors.forename: Linjie
authors.initials: L
authors.lastname: Tian
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Murakami
authors.forename: Dong-Mi
authors.initials: DM
authors.lastname: Shin
authors.forename: Francisco
authors.initials: F
authors.lastname: Borrego
authors.forename: Herbert C
authors.initials: HC
authors.lastname: Morse
authors.forename: John E
authors.initials: JE
authors.lastname: Coligan
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000276:immunology; D000941:Antigens / Q000276:immunology*; D017209:Apoptosis / Q000276:immunology; D015551:Autoimmunity / Q000276:immunology; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D001704:Biopolymers; D001853:Bone Marrow / Q000276:immunology / Q000473:pathology; D018858:Germinal Center / Q000473:pathology; D006706:Homeostasis / Q000276:immunology; D007114:Immunization; D007075:Immunoglobulin M / Q000276:immunology*; D007153:Immunologic Deficiency Syndromes / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D007156:Immunologic Memory; D038041:Lymphopoiesis / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010537:Peritoneum / Q000276:immunology / Q000473:pathology; D010950:Plasma Cells / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D011961:Receptors, Fc / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000276:immunology / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000941:Antigens; D001704:Biopolymers; D007075:Immunoglobulin M; D012333:RNA, Messenger; D011947:Receptors, Antigen, B-Cell; D011961:Receptors, Fc; C035311:immunoglobulin M receptor; C024242:polymeric IgM