Bond Elasticity Controls Molecular Recognition Specificity in Antibody–Antigen Binding

Force-spectroscopy experiments make it possible to characterize single ligand–receptor pairs. Here we measure the spectrum of bond strengths and flexibilities in antibody–antigen interactions using optical tweezers. We characterize the mechanical evolution of polyclonal antibodies generated under infection and the ability of a monoclonal antibody to cross-react against different antigens. Our results suggest that bond flexibility plays a major role in remodeling antibody–antigen bonds in order to improve recognition during the maturation of the humoral immune system.