The V alpha 14 NKT cell TCR exhibits high-affinity binding to a glycolipid/CD1d complex.
Most CD1d-dependent NKT cells in mice have a canonical V alpha 14J alpha 18 TCR rearrangement. However, relatively little is known concerning the molecular basis for their reactivity to glycolipid Ags presented by CD1d. Using glycolipid Ags, soluble forms of a V alpha 14 NKT cell-derived TCR, and mutant and wild-type CD1d molecules, we probed the TCR/CD1d interaction by surface plasmon resonance, tetramer equilibrium staining, and tetramer staining decay experiments. By these methods, several CD1d alpha-helical amino acids could be defined that do not greatly alter lipid binding, but that affect the interaction with the TCR. Binding of the V alpha 14(+) TCR to CD1d requires the agonist alpha-galactosylceramide (alpha-GalCer), as opposed to the nonantigenic beta-galactosylceramide, although both Ags bind to CD1d, indicating that the carbohydrate moiety of the CD1d-bound Ag plays a major role in the TCR interaction. The TCR has a relatively high-affinity binding to the alpha-GalCer/CD1d complex, with a particularly slow off rate. These unique properties are consistent with the coreceptor-independent action of the V alpha 14 TCR and may be related to the intense response to alpha-GalCer by NKT cells in vivo.
Sidobre
Stéphane
S
Division of Developmental Immunology, La Jolla Institute for Allergy and Immunology, San Diego, CA 92121, USA.
Naidenko
Olga V
OV
Sim
Bee-Cheng
BC
Gascoigne
Nicholas R J
NR
Garcia
K Christopher
KC
Kronenberg
Mitchell
M
D017951:Antigen Presentation; D018949:Antigens, CD1 / Q000378:metabolism*; D055610:Antigens, CD1d; D005699:Galactosylceramides / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000378:metabolism*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism*
D018949:Antigens, CD1; D055610:Antigens, CD1d; D005699:Galactosylceramides; D016693:Receptors, Antigen, T-Cell, alpha-beta