PMID: 22261618

Authors:

Chodorge M, Zuger S, Stirnimann C, Briand C, Jermutus L, Grutter MG, Minter RR

Title:

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

Journal:

Cell Death Differ. 2012 Jan 20. doi: 10.1038/cdd.2011.208.

Abstract:

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 A 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.Cell Death and Differentiation advance online publication, 20 January 2012; doi:10.1038/cdd.2011.208.