Melanoma cells present a MAGE-3 epitope to CD4(+) cytotoxic T cells in association with histocompatibility leukocyte antigen DR11.
In this study we used TEPITOPE, a new epitope prediction software, to identify sequence segments on the MAGE-3 protein with promiscuous binding to histocompatibility leukocyte antigen (HLA)-DR molecules. Synthetic peptides corresponding to the identified sequences were synthesized and used to propagate CD4(+) T cells from the blood of a healthy donor. CD4(+) T cells strongly recognized MAGE-3281-295 and, to a lesser extent, MAGE-3141-155 and MAGE-3146-160. Moreover, CD4(+) T cells proliferated in the presence of recombinant MAGE-3 after processing and presentation by autologous antigen presenting cells, demonstrating that the MAGE-3 epitopes recognized are naturally processed. CD4(+) T cells, mostly of the T helper 1 type, showed specific lytic activity against HLA-DR11/MAGE-3-positive melanoma cells. Cold target inhibition experiments demonstrated indeed that the CD4(+) T cells recognized MAGE-3281-295 in association with HLA-DR11 on melanoma cells. This is the first evidence that a tumor-specific shared antigen forms CD4(+) T cell epitopes. Furthermore, we validated the use of algorithms for the prediction of promiscuous CD4(+) T cell epitopes, thus opening the possibility of wide application to other tumor-associated antigens. These results have direct implications for cancer immunotherapy in the design of peptide-based vaccines with tumor-specific CD4(+) T cell epitopes.
Laboratory of Tumor Immunology, Department of Biology and Technology (DIBIT), Scientific Institute H. San Raffaele, 20132 Milan, Italy.
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Hammer
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Protti
D000595:Amino Acid Sequence; D017951:Antigen Presentation; D000951:Antigens, Neoplasm; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D019496:Cancer Vaccines; D003602:Cytotoxicity, Immunologic; D015195:Drug Design; D000939:Epitopes; D005544:Forecasting; D006684:HLA-DR Antigens / Q000276:immunology*; D059810:HLA-DR Serological Subtypes; D006801:Humans; D008213:Lymphocyte Activation; D008545:Melanoma / Q000276:immunology*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012984:Software; D016176:T-Lymphocyte Subsets
D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D000939:Epitopes; D006684:HLA-DR Antigens; D059810:HLA-DR Serological Subtypes; C080766:HLA-DR11 antigen; C072013:MAGEA3 protein, human; D009363:Neoplasm Proteins; D010446:Peptide Fragments