Cutting Edge: Structural Requirements for Galactosylceramide Recognition by CD1-Restricted NK T Cells

Abstract

The reactivity of a group of mouse Vα14+ NK T cell hybridomas was tested with a panel of analogs of the glycolipid α-galactosylceramide (α-GalCer). Interestingly, the nearly complete truncation of the acyl chain from 24 to 2 carbons does not significantly affect the mouse NK T cell response to glycolipid presented by either mouse CD1 (mCD1) or its human homolog CD1d (hCD1d). Therefore, we propose that only one of the two hydrophobic pockets of the CD1 Ag-binding groove needs to be filled by Ag. In terms of the sphingosine base, the mCD1 binding groove has less-demanding structural requirements for presentation to NK T cells than hCD1d. Tests of NK T cell reactivity to analogs presented by hCD1d demonstrates that the invariant TCRs expressed by mouse and human NK T cells are surprisingly similar in their requirements for glycolipid recognition.