A series of Fas receptor agonist antibodies that demonstrate an inverse correlation between affinity and potency

Cell Death Differ. 2012 Jul;19(7):1187-95. doi: 10.1038/cdd.2011.208. Epub 2012 Jan 20.


Receptor agonism remains poorly understood at the molecular and mechanistic level. In this study, we identified a fully human anti-Fas antibody that could efficiently trigger apoptosis and therefore function as a potent agonist. Protein engineering and crystallography were used to mechanistically understand the agonistic activity of the antibody. The crystal structure of the complex was determined at 1.9 Å resolution and provided insights into epitope recognition and comparisons with the natural ligand FasL (Fas ligand). When we affinity-matured the agonist antibody, we observed that, surprisingly, the higher-affinity antibodies demonstrated a significant reduction, rather than an increase, in agonist activity at the Fas receptor. We propose and experimentally demonstrate a model to explain this non-intuitive impact of affinity on agonist antibody signalling and explore the implications for the discovery of therapeutic agonists in general.

MeSH terms

  • Antibodies / genetics
  • Antibodies / immunology*
  • Apoptosis / drug effects
  • Binding Sites
  • Crystallography, X-Ray
  • Fas Ligand Protein / pharmacology
  • HeLa Cells
  • Humans
  • Jurkat Cells
  • Kinetics
  • Mutagenesis
  • Protein Engineering
  • Protein Structure, Tertiary
  • Signal Transduction
  • Single-Chain Antibodies / genetics
  • Single-Chain Antibodies / immunology
  • fas Receptor / agonists*
  • fas Receptor / immunology
  • fas Receptor / metabolism


  • Antibodies
  • Fas Ligand Protein
  • Single-Chain Antibodies
  • fas Receptor