Impact of HLA-DR Antigen Binding Cleft Rigidity on T Cell Recognition.

The interaction between T cell receptor (TCR) and peptide (p)-Human Leukocyte Antigen (HLA) complexes is the critical first step in determining T cell responses. X-ray crystallographic studies of pHLA in TCR-bound and free states provide a structural perspective that can help understand T cell activation. These structures represent a static "snapshot", yet the nature of pHLAs and their interactions with TCRs are highly dynamic.