title: Broadening of epitope recognition during immune rejection of ErbB-2-positive tumor prevents growth of ErbB-2-negative tumor.
abstract: Tumor heterogeneity is a limiting factor in Ag-specific vaccination. Ag-negative variants may arise after tumor cells bearing the immunizing Ags are destroyed. In situ priming to tumor-associated epitopes distinct from and not cross-reactive with the immunizing Ags may be crucial to the ultimate success of cancer vaccination. Immunization of BALB/c mice with DNA encoding wild-type human ErbB-2 (Her-2/neu, E2) or cytoplasmic ErbB-2 (cytE2), activated primarily CD4 or CD8 T cells, respectively, and both vaccines protected against ErbB-2-positive D2F2/E2 tumors. In > or =50% of protected mice, a second challenge of ErbB-2-negative D2F2 tumor cells was rejected. Recognition of non-ErbB-2, tumor-associated Ags was demonstrated by immune cell proliferation upon stimulation with irradiated D2F2 cells. This broadening of epitope recognition was abolished if CD4 T cells were depleted before D2F2/E2 tumor challenge, demonstrating their critical role in Ag priming. Similarly, mice that rejected D2F2/cytE2 tumor cells, which express only MHC I epitopes of ErbB-2, were not protected from a second challenge with D2F2 cells. Depletion of CD8 T cells abolished protection against D2F2, indicating the activation of D2F2-specific CTL. Therefore, long term protection may be achieved by immunization with dominant Ag(s), followed by a general enhancement of CD4 T cell activity to promote priming to multiple tumor-associated Ags.
authors.affiliation: Department of Immunology and Microbiology, Wayne State University, Detroit, MI 48201, USA.
authors.forename: Shari A
authors.initials: SA
authors.lastname: Pilon
authors.forename: Carmen
authors.initials: C
authors.lastname: Kelly
authors.forename: Wei-Zen
authors.initials: WZ
authors.lastname: Wei
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000008:administration & dosage / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism / Q000502:physiology; D018984:Epitopes, T-Lymphocyte / Q000008:administration & dosage / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D006084:Graft Rejection / Q000276:immunology* / Q000378:metabolism*; D006131:Growth Inhibitors / Q000008:administration & dosage / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D008546:Melanoma, Experimental; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000008:administration & dosage / Q000096:biosynthesis* / Q000276:immunology*; D014407:Tumor Cells, Cultured; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000951:Antigens, Neoplasm; D018984:Epitopes, T-Lymphocyte; D006131:Growth Inhibitors; D018719:Erb-b2 Receptor Tyrosine Kinases; D019444:Vaccines, DNA