title: Antigen processing and immune regulation in the response to tumours.
abstract: The MHC class I and II antigen processing and presentation pathways display peptides to circulating CD8+cytotoxic and CD4+helper T cells respectively to enable pathogens and transformed cells to be identified. Once detected, T cells become activated and either directly kill the infected / transformed cells (CD8+cytotoxic T lymphocytes) or orchestrate the activation of the adaptive immune response (CD4+T cells). The immune surveillance of transformed/tumour cells drives alteration of the antigen processing and presentation pathways to evade detection and hence the immune response. Evasion of the immune response is a significant event tumour development and considered one of the hallmarks of cancer. To avoid immune recognition, tumours employ a multitude of strategies with most resulting in a down-regulation of the MHC class I expression at the cell surface, significantly impairing the ability of CD8+cytotoxic T lymphocytes to recognize the tumour. Alteration of the expression of key players in antigen processing not only affects MHC class I expression but also significantly alters the repertoire of peptides being presented. These modified peptide repertoires may serve to further reduce the presentation of tumour-specific/associated antigenic epitopes to aid immune evasion and tumour progression. Here we review the modifications to the antigen processing and presentation pathway in tumours and how it affects the anti-tumour immune response, considering the role of tumour-infiltrating cell populations and highlighting possible future therapeutic targets.
authors.affiliation: Cancer Sciences Unit, Southampton General Hospital, Southampton, UK.|Institute for Life Sciences, University of Southampton, Southampton, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Reeves
authors.affiliation: Cancer Sciences Unit, Southampton General Hospital, Southampton, UK.|Institute for Life Sciences, University of Southampton, Southampton, UK.
authors.forename: Edward
authors.initials: E
authors.lastname: James
mesh_terms: D000818:Animals; D017951:Antigen Presentation; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D019496:Cancer Vaccines / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D006801:Humans; D056747:Immunomodulation; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D009369:Neoplasms / Q000276:immunology*; D019139:Tumor Escape
chemical_list: D019496:Cancer Vaccines
keywords: MHC; antigen processing and presentation; cancer immunology