Lymphocytes stimulated by antigen undergo a process of mutagenesis and selection.
The classical model is undisputed for hapten responses, but whether it applies to protein and viral antigens has become unclear in recent years. In this wholly non-specific intermediate, two reactants have come into proximity and are driven by Brownian motion in a series of collisions, rotations, and translations across each other's surfaces. Experimental evidence for encounter complexes in protein-protein interactions is almost nil. We would like to change that, and are using antibody-antigen interactions as a model system for understanding the kinetics of encounter complex formation. Principal axes of inertia are hypothetical lines about which an object can spin without having its angular momentum diverted in other directions.