Synthetic peptide libraries in the determination of T cell epitopes and peptide binding specificity of class I molecules

Major histocompatibility complex (MHC) class I molecules combine with short peptides of defined length and sequence. Here we describe an approach that may be used in the analysis of peptide preference of different allelic MHC class I molecules, and in the determination of T cell epitopes. We produced synthetic “peptide libraries” of limited complexity by standard peptide chemistry. Using these peptide mixtures we show that H‐2 Kb molecules can accomodate both 8‐and 9‐residue peptides, whereas Db molecules are unable to combine with peptides shorterthan 9 amino acids present in these libraries. When these peptide mixturesare used to provide “fingerprints” of Db molecules and mutants thereof, both loss and gain of the ability to combine with certain peptides is observed. For the Kbm1 mutant a strong influence of amino acid substitutions in class I molecules on the peptides selected is observed. In these synthetic peptide mixtures, the presence ofa specific T cell epitope, known to be represented once, can be detected. This approachmay be extended to the identification of new T cell epitopes from largerpeptide libraries.