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

Invariant human TCR Vα24-Jα18(+)/Vβ11(+) NKT cells (iNKT) are restricted by CD1d–α-glycosylceramides. We analyzed crystal structures and binding characteristics for an iNKT TCR plus two CD1d–α-GalCer–specific Vβ11(+) TCRs that use different TCR Vα 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–α-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)3α, CDR3β, and CDR1β interact with ligands presented by CD1d, whereas CDR2β binds to the CD1d α1 helix. This docking provides an explanation for the dominant usage of Vβ11 and Vβ8.2 chains by human and mouse iNKT cells, respectively, for recognition of CD1d–α-GalCer.