title: Fc receptor homolog 3 is a novel immunoregulatory marker of marginal zone and B1 B cells.
abstract: Two members of the recently identified FcR homolog (FcRH) family in mice demonstrate preferential B cell expression. One of these, FcRH3, encodes a type I transmembrane protein with five extracellular Ig domains and a cytoplasmic tail with a consensus ITIM and a noncanonical ITAM. Analysis of full-length cDNAs from five different mouse strains defines two FcRH3 alleles. A panel of FcRH3-specific mAbs was generated to define its expression pattern and functional potential on B lineage cells. Although poorly detected on the majority of bone marrow or peripheral blood cells, FcRH3 was readily identified on splenic marginal zone (MZ) and MZ precursor B cells, but not on the bulk of newly formed B cells, follicular B cells, germinal center B cells, and plasma cells. In the peritoneal cavity, FcRH3 was found on B1 cells, and not on the majority of B2 cells. Consistent with its possession of an ITIM and ITAM-like sequence, FcRH3 was tyrosine phosphorylated following pervanadate treatment, and its coligation with the BCR inhibited calcium mobilization. These results suggest FcRH3 is a novel immunoregulatory marker of MZ and B1 B lineage cells.
authors.affiliation: Division of Developmental and Clinical Immunology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Woong-Jai
authors.initials: WJ
authors.lastname: Won
authors.forename: Jeremy B
authors.initials: JB
authors.lastname: Foote
authors.forename: Mary R
authors.initials: MR
authors.lastname: Odom
authors.forename: Jicun
authors.initials: J
authors.lastname: Pan
authors.forename: John F
authors.initials: JF
authors.lastname: Kearney
authors.forename: Randall S
authors.initials: RS
authors.lastname: Davis
mesh_terms: D000483:Alleles; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D002478:Cells, Cultured; D005260:Female; D007126:Immunoglobulin Allotypes / Q000378:metabolism; D007155:Immunologic Factors / Q000096:biosynthesis*; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008814:Mice, Inbred NZB; D008822:Mice, Transgenic; D011961:Receptors, Fc / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D013234:Stem Cells / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D015415:Biomarkers; C515879:FcRH3 protein, mouse; D007126:Immunoglobulin Allotypes; D007155:Immunologic Factors; D011961:Receptors, Fc