Active mechanical patterning of the immune synapse

Immune cells make rapid cellular decisions using receptor proteins that organize in complex spatial patterns on their membrane, called the immunological synapse. While much is known about how molecular kinetics controls antigen discrimination and immune cell activation, the role of active forces in synapse patterning and recognition is less explored. Recent experiments suggest that B-cells exert active forces that enables mechanical discrimination of antigens. Using a minimal continuum description coupling membrane elastohydrodynamics, active forces, and receptor kinetics, we identify active mechanisms that create arrested multifocal patterns and generate coarsening, reminiscent of synaptic patterns observed in both naive and mature B-cells. We quantify how mechanical forces can tune the sensitivity of B-cells to antigen affinities and suggest experimental tests of the results. Our work highlights the under-appreciated role of the physical environment of cells in immune recognition.