A new understanding of the T-cell recognition process has been revealed by describing how T-cell receptors use mechanical contact – the forces involved in their binding to antigens – to make decisions about whether or not the cells they encounter are threats. “This is the first systematic study of how T-cell recognition is affected by mechanical force, and it shows that forces play an important role in the functions of T-cells,” said a co-author. “We think that mechanical force plays a role in almost every step of T-cell biology.”