title: Expression of the G-protein--coupled receptor BLR1 defines mature, recirculating B cells and a subset of T-helper memory cells.
abstract: The G-protein-coupled receptor BLR1 related to receptors for chemokines and neuropeptides has been identified as the first lymphocyte-specific member of the gene family characterized by seven transmembrane-spanning regions. Using a high-affinity anti-BLR1 monoclonal antibody (MoAb) and three-color flow cytometry it is shown that BLR1 expression on peripheral blood cells is limited to B cells and to a subset of CD4+ (14%) and CD8+ (2%) lymphocytes. T cells expressing BLR1 were positive for CD45R0, were negative for interleukin-2 receptors, show high levels of CD44, and show low levels of L-selectin. The majority of CD4+ cells originating from secondary lymphatic tissue, but none of cord blood-derived T cells, express BLR1. These observations suggest that BLR1 is a marker for memory T cells. Furthermore, BLR1 expression was detected on all CD19+ peripheral or tonsillar B lymphocytes, but only on a fraction of cord blood cells and bone marrow cells expressing CD19, sIgM, or sIgD. Interestingly, activation of both mature B and T cells by CD40 MoAb and CD3 MoAb, respectively, led to complete downregulation of BLR1. These data suggest that the G-protein-coupled receptor BLR1 is involved in functional control of mature recirculating B cells and T-helper memory cells participating in cell migration and cell activation.
authors.affiliation: Max-Delbrück-Center for Molecular Medicine, Berlin-Buch, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Förster
authors.forename: T
authors.initials: T
authors.lastname: Emrich
authors.forename: E
authors.initials: E
authors.lastname: Kremmer
authors.forename: M
authors.initials: M
authors.lastname: Lipp
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D016175:B-Lymphocyte Subsets / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D002675:Child, Preschool; D015536:Down-Regulation; D005434:Flow Cytometry; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007156:Immunologic Memory; D016130:Immunophenotyping; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets / Q000378:metabolism*; D014066:Palatine Tonsil / Q000166:cytology; D010954:Plasmacytoma / Q000378:metabolism; D054380:Receptors, CXCR5; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine / Q000378:metabolism*; D013154:Spleen / Q000166:cytology; D006377:T-Lymphocytes, Helper-Inducer / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000944:Antigens, Differentiation, B-Lymphocyte; D000945:Antigens, Differentiation, T-Lymphocyte; C095085:CXCR5 protein, human; D054380:Receptors, CXCR5; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine; D019204:GTP-Binding Proteins