MHC-restricted, glycopeptide-specific T cells show specificity for both carbohydrate and peptide residues.

We examined the antigenic specificity of two T cell hybridomas elicited against the disaccharide galabiose attached to the fifth residue of the I-Ak binding peptide 52-61 of lysozyme. By making changes in the saccharide molecule and in the peptide, we conclude that the outer galactose residue of the galabiose moiety is directly recognized by the T cells together with the exposed side chains of the peptide. The overall spatial display of this galactose moiety on the 52-61 peptide is likewise important.