Chimeric anti-TNF-alpha Monoclonal Antibody cA2 Binds Recombinant Transmembrane TNF-alpha and Activates Immune Effector Functions

Cytokine. 1995 Apr;7(3):251-9. doi: 10.1006/cyto.1995.0029.

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.

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Antigen-Antibody Reactions
  • Base Sequence
  • Complement System Proteins / immunology
  • Cytotoxicity, Immunologic
  • Humans
  • Infliximab
  • Lymphocyte Activation
  • Membrane Proteins / immunology*
  • Mice
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / immunology*
  • Recombinant Proteins / immunology
  • T-Lymphocytes, Regulatory / immunology*
  • Tumor Necrosis Factor-alpha / immunology*

Substances

  • Antibodies, Monoclonal
  • Membrane Proteins
  • Recombinant Fusion Proteins
  • Recombinant Proteins
  • Tumor Necrosis Factor-alpha
  • Complement System Proteins
  • Infliximab