A kinetic differentiation model for the action of altered TCR ligands

T-cell receptor (TCR) recognition of the peptide-major histocompatibility c omplex (MHC) can lead to quantitatively and qualitatively different respons es depending on the nature of the bound ligand. Subtly altered peptide liga nds might net as partial agonists, antagonists or null ligands. Here, Graha m Loud and colleagues propose a kinetic differentiation model to explain ho w altered TCR signalling can occur.