The MHC class-I binding affinity of an
epitope is an important parameter determining the immunogenicity of the
peptide-MHC complex. In order to improve the immunogenicity of an
epitope derived from
melanocyte lineage-specific antigen gp100, we performed amino-acid substitutions within the
epitope and assayed both
HLA-A*0201 binding and CTL recognition. Anchor replacements towards the
HLA-A*0201 peptide-binding motif gave rise to
peptides with higher
HLA-A*0201 binding capacity compared to the wild-type
epitope. In addition, several of the gp100 154-162
epitope-analogues were more efficient at target-cell sensitization for lysis by anti-gp100 154-162 CTL compared to the wild-type
epitope. These altered gp100 154-162
epitopes were subsequently tested for their capacity to induce CTL responses in vivo using
HLA-A*0201/Kb transgenic mice, and in vitro using
HLA-A*0201 + donor-derived lymphocytes. Interestingly, the
peptide-specific CTL obtained, which were raised against the different gp100 154-162
epitope-analogues, displayed cross-reactivity with target cells endogenously processing and presenting the native
epitope. These data demonstrate that altered
epitopes can be exploited to elicit native
epitope-reactive CTL. The use of
epitope-analogues with improved immunogenicity may contribute to the development of CTL-
epitope based
vaccines in
viral disease and
cancer.