Significance The ability of a T cell to explore environmental mechanical cues, through bonds formed by its special receptors called T cell receptors (TCRs), is crucial for the first steps of immune recognition. Here we show that the response of T cells, quantified in terms of their spreading behavior, is biphasic with substrate stiffness when mediated through TCRs. However, when the ligands of the T cell integrins are additionally involved, the cellular response becomes monotonic. Based on a mesoscale model, this ligand-specific response can be attributed to differences in force sensitivity and effective stiffness of the link formed between the ligand/receptor pairs and the actin cytoskeleton. This may provide a general mechanism for immune cells to discriminate mechanosensitive bonds.