Physics-Biology interface seminar: Paolo Pierobon


11:00 - 12:00

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Mechanics of B cell response

Paolo Pierobon (Institut Curie, Paris)

B lymphocytes are the antibodies producing cells and therefore essential effectors of adaptive immunity. In vivo, their activation is mostly triggered by the engagement of their B cell receptor (BCR) with antigens exposed at the surface of neighbouring antigen presenting cells. This leads to the formation of a signalling platform, the immune synapse, where cytoskeleton rearrangement are essential for the antigen extraction, internalization and processing. While it has been shown that on a hard substrate the cell follows a dynamics of spreading and contraction, this has never been investigated on substrates with rigidity close to the physiological one. We measure for the first time the forces produced by B cells on deformable antigen coated surfaces (traction force microscopy) and show that these forces are contractile, specifically induced by BCR activation and Myosin II dependent. We characterize the contractile dynamics of the cell and argue that in generating pulling forces, Myosin II plays a crucial role in antigen gathering and internalization. These results open interesting perspectives on the role of mechanics in the acquisition of specific antigen and more generally on receptor internalization.

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