Tumor Escape Mutants Develop within an Immune-Privileged Environment in the Absence of T Cell Selection

• Published in: Journal of Immunology 2006-07, Vol.177 (1), p.162-168
• Main Authors: Chen, Peter W, Uno, Toshihiko, Ksander, Bruce R
• Format: Article
• Language: English
• Subjects: Animals; Anterior Chamber - immunology; Anterior Chamber - pathology; Cell Line, Tumor; Cytotoxicity, Immunologic - genetics; Down-Regulation - immunology; Eye Neoplasms - genetics; Eye Neoplasms - immunology; Eye Neoplasms - pathology; Female; Graft Rejection - genetics; Graft Rejection - immunology; H-2 Antigens - biosynthesis; Intercellular Adhesion Molecule-1 - biosynthesis; Leukemia L1210; Lymphocyte Activation - genetics; Lymphocyte Culture Test, Mixed; Mice; Mice, Inbred DBA; Mice, SCID; Neoplasm Transplantation; Phenotype; T-Lymphocyte Subsets - immunology; T-Lymphocyte Subsets - pathology; T-Lymphocytes, Cytotoxic - immunology; T-Lymphocytes, Cytotoxic - pathology; Tumor Escape - genetics; Tumor Escape - immunology
• ISSN: 0022-1767; 1550-6606; 1365-2567
• DOI: 10.4049/jimmunol.177.1.162

The establishment of tumor escape mutants, which can be driven by innate and/or adaptive immune effector cells, presents a significant obstacle in the development of successful tumor immunotherapies. Our study documents that tumors growing within an immune-privileged site within the eye develop a tumor escape phenotype in the absence of selective T cell pressure. P815 tumor cells that are recovered from progressively growing tumors within the anterior chamber of the eye escape elimination when injected into the flanks of a second group of syngeneic DBA/2 mice that were previously immunized against P815 tumor cells. The escape phenotype of eye-derived P815 tumors was stable and permanent when the tumor cells were cultured in vitro. Eye-derived tumor cells recovered from the anterior chamber of CB-17 SCID mice also escaped elimination when injected into the flanks of immunized mice, demonstrating that selective pressure by tumor Ag-specific T cells did not contribute to the development of the escape phenotype. In vitro studies demonstrated that eye-derived tumor cells were not lysed by specific CTL and were unable to restimulate primed Ag-specific T cells. Immune escape of eye-derived tumor cells was not due to down-regulation of either MHC class I or ICAM-1. Our data demonstrate that the immune-privileged environment within the eye induces a tumor escape phenotype that is not driven by selective T cell pressure. We predict that immune escape within the eye is driven by the unique ocular environment that permanently alters gene expression in eye-derived tumor cells.