Loss of mechanical stiffness and the emergence of Lévy walks in active T cells

The activation of T cells by the detection of substances not recognized by the immune system results in a more than threefold reduction of their mechanical stiffness and can also result in the occurrence of movement patterns that resemble Lévy walks. Here I show that Lévy walks with the run-pause characteristics of T cells have similitude with the predicted and observed movements of highly deformable particles. Predicted shape-dependent movements are consistent with observations of T cells progressing by a series of repeated lunges, becoming elongated while moving rapidly and balling up when paused.