title: In vivo priming of two distinct antitumor effector populations: the role of MHC class I expression.
abstract: Downregulation of major histocompatibility complex (MHC) class I expression is an important mechanism by which tumors evade classical T cell-dependent immune responses. Therefore, a system was designed to evaluate parameters for active immunization against MHC class I- tumors. Mice were capable of rejecting a MHC class I- tumor challenge after immunization with an irradiated granulocyte/macrophage colony-stimulating factor (GM-CSF) transduced MHC class I- tumor vaccine. This response was critically dependent on CD4+ T cells and natural killer (NK) cells, but minimally on CD8+ T cells. A strong protective response against MHC class I+ variants of the tumor could be elicited when mice were immunized with irradiated MHC class I+ GM-CSF-secreting tumor cells. This response required CD4+ and CD8+ T cells, and in addition, elimination of NK cells resulted in outgrowth of tumors that had lost expression of at least one MHC class I gene. Finally, class I MHC expression on the vaccinating cells inhibited the response generated against a MHC class I- tumor challenge. These results demonstrate that the host is capable of being immunized against a tumor that has lost MHC class I expression and reveal conditions under which distinct effector cells play a role in the systemic antitumor immune response.
authors.affiliation: Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors.forename: H I
authors.initials: HI
authors.lastname: Levitsky
authors.forename: A
authors.initials: A
authors.lastname: Lazenby
authors.forename: R J
authors.initials: RJ
authors.lastname: Hayashi
authors.forename: D M
authors.initials: DM
authors.lastname: Pardoll
mesh_terms: D000818:Animals; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D004247:DNA; D015536:Down-Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000008:administration & dosage / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured; D014611:Vaccination
chemical_list: D015395:Histocompatibility Antigens Class I; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D004247:DNA