The specificity of a weak gamma delta TCR interaction can be modulated by the glycosylation of the ligand

The gamma delta T cell clone LBK5 recognizes the MHC molecule IEk. Here, we demonstrate that the affinity of this interaction is weaker than those typ ically reported for alpha beta TCRs that recognize peptide/MHC complexes. C onsistent with our previous finding that peptide bound to the IE molecule d oes not confer specificity, we show that the entire epitope for LBK5 is con tained within the polypeptide chains of the molecule, centered around the p olymorphic residues 67 and 70 of the IE beta-chain. However, LBK5 recogniti on is profoundly influenced by the N-linked glycosylation at residue 82 of the IE alpha-chain. Since infected, stressed, or transformed cells often ch ange the posttranslational modifications of their surface glycoproteins, th is finding suggests a new way in which gamma delta T cell Ag recognition ca n be regulated.