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Immunity. 2001 Jul;15(1):59-70.

The impact of duration versus extent of TCR occupancy on T cell activation: a revision of the kinetic proofreading model.

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Department of Laboratory Medicine and Pathology, Center for Immunology, University of Minnesota, Minneapolis, MN 55455, USA.


The widely accepted kinetic proofreading theory proposes that rapid TCR dissociation from a peptide/MHC ligand allows for stimulation of early but not late T cell activation events, explaining why low-affinity TCR ligands are poor agonists. We identified a low-affinity TCR ligand which stimulated late T cell responses but, contrary to predictions from kinetic proofreading, inefficiently induced early activation events. Furthermore, responses induced by this ligand were kinetically delayed compared to its high-affinity counterpart. Using peptide/MHC tetramers, we showed that activation characteristics could be dissociated from TCR occupancy by the peptide/MHC ligands. Our data argue that T cell responses are triggered by a cumulative signal which is reached at different time points for different TCR ligands.

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