Ligation of human Fc receptor like-2 (FCRL2) by specific monoclonal antibodies downregulates B cell receptor mediated signaling
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1
Avicenna Research Institute,, Department of Antibody and Antigen Engendering, Iran
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2
Shiraz University of Medical Sciences, Department of Immunology, Medical School, Iran
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3
University of Siena, Department of Evolutionary Biology, Italy
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4
Tehran University of Medical Sciences, Department of Immunology, School of Public Health, Iran
Introduction: B cell antigen receptor (BCR) signaling and its regulation are critical for balancing B cell response and function. Human Fc receptor like-2 (FCRL2) could influence B cell signaling due to possession of both activating and inhibitory tyrosine-based immunoregulatory motifs. Since the natural ligand of FCRL2 has not been identified yet, we generated FCRL2-specific monoclonal antibodies (mAbs) and employed them to investigate the influence of FCRL2 stimulation on BCR signaling in FCRL2 expressing B cell line. Methods: Anti-FCRL2 secreting hybridomas were produced using hybridoma technology and screened with the immunizing protein by ELISA and stable CHO cell line expressing FCRL2 protein by FACS. The CA46 cells (FCRL2 positive) were stimulated in different condition using different concentration of anti-IgM Ab and mAbs to FCRL2 followed by BCR mediators analysis by FACS and Immunoblotting. Results: Two hybridoma clones producing mAbs specific for FCRL2 were selected (5A7-E7 and 3D8-G8). Both mAbs displayed no cross-reactivity with the other members of the FCRL family as tested by FACS and ELISA techniques. Engagement of FCRL2 by these mAbs resulted in significant inhibition of BCR signaling mediators such as calcium mobilization, phosphorylation of Erk, p38 and Jnk MAP kinases. A minor or no inhibition of the phosphorylation of whole protein tyrosine, Syk, Vav and Akt observed in B cells treated with a cocktail of anti-FCRL2 and anti-BCR Abs. Conclusion: These findings indicated that the FCRL2 ITIMs motifs are functional and the anti-FCRL2 mAbs may mimic the natural ligand of FCRL2 by induction of inhibitory signals in B cells.
Keywords:
FCRL2,
Monoclonal antibody,
BCR signaling,
BL cell line,
MAP Kinase Signaling System
Conference:
15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013.
Presentation Type:
Abstract
Topic:
Immune receptors and signaling
Citation:
Shabani
M,
Bayat
A,
Jeddi-Tehrani
M,
Rabbani
H,
Ulivieri
C,
Amirghofran
Z,
Baldari
CT and
Shokri
F
(2013). Ligation of human Fc receptor like-2 (FCRL2) by specific monoclonal antibodies downregulates B cell receptor mediated signaling.
Front. Immunol.
Conference Abstract:
15th International Congress of Immunology (ICI).
doi: 10.3389/conf.fimmu.2013.02.00778
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Received:
17 Jun 2013;
Published Online:
22 Aug 2013.
*
Correspondence:
Prof. Fazel Shokri, Tehran University of Medical Sciences, Department of Immunology, School of Public Health, Tehran, Iran, fazshok@yahoo.com