title: Her-2/ neu altered peptide ligand-induced CTL responses: implications for peptides with increased HLA affinity and T-cell-receptor interaction.
abstract: In this study, we developed two Her-2/ neu-derived E75 altered peptide ligands (APLs) that demonstrate increased affinities for the HLA-A*0201 allele compared with wild-type E75 peptide. The APLs contain amino acids from E75(369-377), an immunodominant Her-2/ neu-derived peptide, and preferred primary and auxiliary HLA-A*0201 molecule anchor residues previously identified from combinatorial peptide library screening with the recombinant molecule. CTL lines were generated against wild-type E75 peptide (KIFGSLAFL) and APLs by multiple rounds of peptide stimulation of peripheral blood mononuclear cells (PBMCs) from HLA-A2+ antigen normal individuals. CTL lines raised on wild-type E75 peptide cross-reacted with APLs and similarly, CTL lines raised on APLs cross-reacted with wild-type E75 peptide, as measured by IFN-gamma ELISpot and target cell lysis assays. One of five individuals demonstrated specificity for APL 2 (FLFGSLAFL), whereas APL 5 (FLFESLAFL)-specific responses were observed from all five individuals tested. Molecular models of the E75, APL 2, and APL 5/HLA-A2 complexes indicated that the substitution of glycine with glutamic acid at position four of APL 5 resulted in the presentation of a large, negatively charged side chain that interacts with the outer edge of the HLA-A2 antigen alpha helix and is freely available to interact with cognate T-cell receptors. The results of this study further substantiate the concept that rational design of T-cell epitopes may lead to stronger peptide immunogens than natural, wild-type peptides.
authors: Department of Microbiology and Immunology, Arizona Cancer Center, University of Arizona, 1515 North Campbell Avenue, Tucson, AZ 85724, USA.
authors: Sara O
authors: SO
authors: Dionne
authors: Cheryl E
authors: CE
authors: Myers
authors: Margaret H
authors: MH
authors: Smith
authors: Douglas F
authors: DF
authors: Lake
mesh_terms: D000951:Antigens, Neoplasm / Q000276:immunology*; D003601:Cytotoxicity Tests, Immunologic; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D015234:HLA-A Antigens / Q000276:immunology*; D015789:HLA-A2 Antigen; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D010446:Peptide Fragments / Q000276:immunology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D000951:Antigens, Neoplasm; D018984:Epitopes, T-Lymphocyte; D015234:HLA-A Antigens; D015789:HLA-A2 Antigen; D008024:Ligands; D010446:Peptide Fragments; D018719:Erb-b2 Receptor Tyrosine Kinases; D011948:Receptors, Antigen, T-Cell; C435939:HLA-A*02:01 antigen