title: 70 kDa heat shock cognate protein is a transformation-associated antigen and a possible target for the host's anti-tumor immunity.
abstract: We previously investigated a novel heat-inducible transformation-associated cell surface Ag that is expressed on the activated H-ras oncogene-transformed rat fibrosarcoma W31, but not its parental nontransformed fibroblast WFB. This Ag was detected by mAb 067. Herein, we characterized the molecular nature of the Ag by using anti-heat shock protein (HSP) mAb. The accumulated data indicated that the cell surface expression of Ag was clearly enhanced by several stressors, such as TNF, L-azetidine-2-carboxylic acid, and sodium arsenite. The immunoprecipitate made with mAb 067 and W31 cell lysates reacted with anti-rat 70 kDa heat shock cognate (HSC) mAb, TG5E, indicating that 067-defined Ag may be a rat 70 kDa HSC. Because this Ag seemed to be one of the transformation-associated Ag of WFB, we further studied whether it could play an important role in the host's anti-tumor immunity. Peripheral T cells of rats primed with live BCG showed cytotoxicity to W31 but not to WFB. Because the possibility existed that HSP may interact with certain populations of T cells, we focused on the reactivity of CD4-CD8- double negative T (DNT) cells against 067-defined molecule. DNT cells from spleen and PBL of live BCG-primed rats showed the cytotoxicity against W31 cells. This cytotoxicity was completely blocked by mAb 067 and anti-CD3 mAb. However, it was not blocked by mAb R48B1 and 109, which detect the MHC class I nonpolymorphic determinant and a target molecule of the cytolysis by poly I:C-induced NK cells, respectively. Furthermore, brefeldin A was able to block the cytotoxicity against W31 targets by DNT cells, but not by NK cells. These data suggest that 70 kDa HSC may be a tumor Ag and may act as a presenting molecule perhaps complexed with cellular peptides to certain DNT cells.
authors.affiliation: Department of Pathology, Sapporo Medical University School of Medicine, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tamura
authors.forename: N
authors.initials: N
authors.lastname: Tsuboi
authors.forename: N
authors.initials: N
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Kikuchi
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000951:Antigens, Neoplasm / Q000032:analysis / Q000276:immunology*; D001692:Biological Transport; D020126:Brefeldin A; D003517:Cyclopentanes / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic; D006360:Heat-Shock Proteins / Q000032:analysis / Q000276:immunology*; D008970:Molecular Weight; D009369:Neoplasms / Q000276:immunology*; D051381:Rats; D011919:Rats, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D003517:Cyclopentanes; D006360:Heat-Shock Proteins; D020126:Brefeldin A