Abstract
T lymphocytes recognize their antigenic targets as peptides associated with major histocompatibility complex molecules. The HLA-A11 allele, a preferred restriction element for Epstein-Barr virus (EBV)-specific cytotoxic T-lymphocyte responses, presents an immunodominant epitope derived from the EBV nuclear antigen 4. Subpicomolar concentrations of a synthetic nonamer peptide, IVTDFSVIK, corresponding to amino acids 416-424 of the EBV nuclear antigen 4 sequence, can sensitize phytohemagglutinin-stimulated blasts to lysis by EBV-specific HLA-A11-restricted cytotoxic T-lymphocytes. We show that micromolar concentrations of this peptide induce assembly and surface expression of HLA-A11 in an A11-transfected subline of the peptide transporter mutant cell line T2. Using the IVTDFSVIK peptide and a series of synthetic nonamer peptides, differing from the original sequence by single amino acid substitutions, we have defined a motif for HLA-A11-binding peptides. This predicts the presence of a hydrophobic amino acid in position 2, amino acids with small side chains in positions 3 and 6, and a lysine in position 9. Using this motif, we have identified a peptide in the carboxyl-terminal end of wild-type p53, ELNEALELK, which is able to induce HLA-A11 assembly as efficiently as the IVTDFSVIK viral peptide.