title: Chimeric anti-TNF-alpha monoclonal antibody cA2 binds recombinant transmembrane TNF-alpha and activates immune effector functions.
abstract: Results of clinical trials have indicated that cA2, a neutralizing mouse/human IgG1 chimeric anti-human TNF-alpha monoclonal antibody, may have therapeutic benefit for rheumatoid arthritis patients. Arthritic joints contain, in addition to elevated levels of soluble TNF-alpha, high numbers of CD4+ T cells and macrophages, cells known to express transmembrane TNF-alpha upon activation. For that reason, we sought to determine if cA2 binds to transmembrane TNF-alpha and what effects such binding may have on TNF-alpha-expressing cells. A cell line expressing a cell-surface, mutant form of transmembrane TNF-alpha was prepared for these studies. Analysis of these TNF+ cells by flow cytometry, direct binding, and competitive binding assays showed that cA2 binds to the transmembrane form of TNF-alpha with high avidity. Binding of the IgG1 isotype of cA2, but not an IgG4 version of cA2, resulted in efficient killing of the TNF+ cells by both antibody-dependent cellular toxicity and complement-dependent cytotoxicity effector mechanisms. These findings indicate that, in addition to blocking soluble TNF-alpha activity, cA2 can bind to transmembrane TNF-alpha in vitro and suggest that cA2 binding may lead to lysis of TNF-alpha-expressing cells in vivo.
authors.affiliation: Department of Molecular Biology, Centocor, Inc., Malvern, PA 19355, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Scallon
authors.forename: M A
authors.initials: MA
authors.lastname: Moore
authors.forename: H
authors.initials: H
authors.lastname: Trinh
authors.forename: D M
authors.initials: DM
authors.lastname: Knight
authors.forename: J
authors.initials: J
authors.lastname: Ghrayeb
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000937:Antigen-Antibody Reactions; D001483:Base Sequence; D003165:Complement System Proteins / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D006801:Humans; D000069285:Infliximab; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D003165:Complement System Proteins; D000069285:Infliximab