Signal strength regulates antigen-mediated T-cell deceleration by distinct mechanisms to promote local exploration or arrest

Significance

To mount an efficient immune response, T cells need to recognize foreign antigen to become activated, proliferate, and acquire their effector functions. We show that T cells can adopt two behaviors depending on the strength of the antigen stimulation. Upon suboptimal stimulation, T cells adopt a scanning behavior that promotes local exploration of the microenvironment. Stronger stimulation triggers specific mechanisms that induce complete T-cell arrest. We propose that these distinct behaviors may represent an optimal strategy for T cells to find the strongest antigenic stimulation.