title: Ligation of human Fc receptor like-2 by monoclonal antibodies down-regulates B-cell receptor-mediated signalling.
abstract: B-cell antigen receptor (BCR) signalling and its regulation through negative and positive regulators are critical for balancing B-cell response and function. Human Fc receptor like-2 (FCRL2), a member of the newly identified FCRL family, could influence B-cell signalling due to possession of both immunoreceptor tyrosine-based activation and inhibitory motifs (ITAM and ITIM). Since the natural ligand of FCRL2 has not been identified, we generated FCRL2-specific monoclonal antibodies (mAbs) and employed them to investigate the influence of FCRL2 stimulation on BCR signalling in an FCRL2-expressing B-cell line. Two anti-FCRL2 mAb-producing hybridoma clones (5A7-E7 and 3D8-G8) were selected. None of the mAbs displayed any cross-reactivity with the other members of the FCRL family including recombinant FCRL1, -3, -4 and -5, as tested by FACS and ELISA techniques. Engagement of the FCRL2 by these mAbs resulted in significant inhibition of BCR signalling mediators such as calcium mobilization and phosphorylation of the mitogen-activated protein kinases Erk, p38 and Jnk. These findings indicate that the FCRL2 ITIM motifs are functional and the anti-FCRL2 mAbs may mimic the natural ligand of FCRL2 by induction of inhibitory signals in B cells.
authors.affiliation: Monoclonal Antibody Research Centre, Avicenna Research Institute, ACECR, Tehran, Iran; Department of Immunology, Medical School, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Shabani
authors.forename: Ali Ahmad
authors.initials: AA
authors.lastname: Bayat
authors.forename: Mahmood
authors.initials: M
authors.lastname: Jeddi-Tehrani
authors.forename: Hodjatallah
authors.initials: H
authors.lastname: Rabbani
authors.forename: Mohammad
authors.initials: M
authors.lastname: Hojjat-Farsangi
authors.forename: Cristina
authors.initials: C
authors.lastname: Ulivieri
authors.forename: Zahra
authors.initials: Z
authors.lastname: Amirghofran
authors.forename: Cosima Tatiana
authors.initials: CT
authors.lastname: Baldari
authors.forename: Fazel
authors.initials: F
authors.lastname: Shokri
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism* / Q000494:pharmacology; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003412:Cricetulus; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; C422179:FCRL2 protein, human; D011947:Receptors, Antigen, B-Cell; D011956:Receptors, Cell Surface; D002118:Calcium
keywords: B-cell receptor signalling; Fc receptor like-2; monoclonal antibody