This article presents the evidence that immune cells are regulating very rapidely, even before classical signalling times as recorded by calcium fluxes, their mechanical properties when encountering an activating substrate, being either artificial (bead) or physiological (APC). For this, we developed a micropipette-based rheometer to track cell viscous and elastic properties. We have shown that leukocytes become up to 10 times stiffer and more viscous during their activation. Elastic and viscous properties evolve in parallel, preserving a ratio characteristic of the leukocyte subtype. These mechanical measurements set up a complete picture of the mechanics of leukocyte activation and provide a signature of cell function

https://doi.org/10.1016/

Activation of three types of leukocytes studied with the micropipette rheometer. Left (a): T cell, middle (b): B cell, right (c): PLB cells. All bars represent 5 μm.