Structure and binding kinetics of three different human CD1d-α-agalactosylceramide-specific T cell receptors

Invariant human TCR V alpha 24-J alpha 18(+)/V beta 11+NKT cells (iNKT) are restricted by CD1d-alpha-glycosylceramides. We analyzed crystal structures and binding characteristics for an iNKT TCR plus two CD1d-alpha-GalCer-specific V beta 11(+) TCRs that use different TCR V alpha chains. The results were similar to those previously reported for MHC-peptide-specific TCRs, illustrating the versatility of the TCR platform. Docking TCR and CD1d-alpha-GalCer structures provided plausible insights into their interaction. The model supports a diagonal orientation of TCR on CD1d and suggests that complementarity determining region (CDR)3 alpha, CDR3 beta, and CDR1 beta interact with ligands presented by CD1d, whereas CDR2 beta. binds to the CD1d alpha 1 helix. This docking provides an explanation for the dominant usage of V beta 11 and V beta 8.2 chains by human and mouse iNKT cells, respectively, for recognition of CD1d-alpha-GalCer.