title: Generation of anti-NAG-2 mAb from patients' memory B cells: implications for a novel therapeutic strategy in systemic sclerosis.
abstract: We have previously reported that antibodies directed against the cytomegalovirus-derived protein UL94 cross react with the cell surface tetraspanin transmembrane 4 superfamily member 7 (TM4SF7 or NAG-2) molecule inducing apoptosis of endothelial cells and activation of fibroblasts in patients with systemic sclerosis (SSc). We aimed at generating a non-functional mAb directed against NAG-2 from patients' memory B cells. Direct and competitive ELISA methods have been used to evaluate the binding of antibodies from scleroderma patients' and controls' sera to the NAG-2 peptide. IgG memory B cells were sorted, EBV transformed and cloned to obtain NAG-2-specific mAbs. Endothelial cells and fibroblasts were cultured under standard conditions and used for functional assays. Anti-NAG-2-purified antibodies obtained from patients' Ig induce endothelial cell apoptosis and fibroblast proliferation. Patients' Igs depleted of the anti-NAG-2 fraction do not exert such functional activity. Therefore, the NAG-2 molecule represents a potential novel candidate for therapeutic intervention in SSc. Here, we describe the generation of a human mAb directed against the NAG-2 molecule. Such mAb does not retain any functional property and is able to block the effect of serum pathogenetic anti-NAG-2 antibodies. The majority of SSc patients present antibodies directed against tetraspanin NAG-2 and mediate both endothelial cell apoptosis and fibroblast proliferation, features of the disease. The anti-NAG-2 human mAb we have obtained blocks signal transduction and therefore may be a potential candidate for a new treatment in SSc, a disease where the current biological therapies have little or no efficacy.
authors.affiliation: Department of Clinical and Experimental Immunology, Institute G. Gaslini, Largo Girolamo Gaslini, 16147 Genova, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Traggiai
authors.forename: Claudio
authors.initials: C
authors.lastname: Lunardi
authors.forename: Caterina
authors.initials: C
authors.lastname: Bason
authors.forename: Marzia
authors.initials: M
authors.lastname: Dolcino
authors.forename: Elisa
authors.initials: E
authors.lastname: Tinazzi
authors.forename: Roberto
authors.initials: R
authors.lastname: Corrocher
authors.forename: Antonio
authors.initials: A
authors.lastname: Puccetti
mesh_terms: D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000096:biosynthesis* / Q000276:immunology / Q000494:pharmacology / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D049109:Cell Proliferation / Q000187:drug effects; D015195:Drug Design; D005260:Female; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology*; D008297:Male; D008565:Membrane Proteins / Q000276:immunology*; D008875:Middle Aged; D012595:Scleroderma, Systemic / Q000188:drug therapy* / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D059470:Tetraspanins; D055815:Young Adult
chemical_list: D000911:Antibodies, Monoclonal; D008565:Membrane Proteins; C109139:TSPAN4 protein, human; D059470:Tetraspanins