Augmenting major histocompatibility complex class I expression by murine tumors in vivo enhances antitumor immunity induced by an active immunotherapy strategy.

Publication Type	Academic Article
Authors	Merritt R, Yamada R, Crystal R, Korst R
Journal	J Thorac Cardiovasc Surg
Volume	127
Issue	2
Pagination	355-64
Date Published	02/01/2004
ISSN	0022-5223
Keywords	Carcinoma, Lewis Lung, Genes, MHC Class I, Immunotherapy, Active, Lung Neoplasms
Abstract	OBJECTIVE: Tumors down-regulate major histocompatibility complex class I expression, escaping recognition by the cellular immune response. We hypothesized that augmentation of tumor cell class I expression by interferon-gamma would enhance the cellular antitumor immune response and cure rate of an active immunotherapy strategy. METHODS: B16.F10 tumor cells were exposed to interferon-gamma in culture, and class I expression was quantified using flow cytometry. Syngeneic mice bearing established tumors were injected with interferon-gamma (5000 U, intraperitoneal), and class I expression was assessed using immunohistochemistry. Tumor-specific cytotoxic T lymphocytes were induced in mice by an intratumoral injection of AdCD40L (5 x 10(10) particles), an adenovirus gene transfer vector-based immunotherapy strategy previously demonstrated to augment cellular antitumor immunity. A conjugate-formation assay and the enzyme-linked immunospot assay were used to evaluate the binding and activation of cytotoxic T lymphocytes, respectively. Interferon-gamma was administered to tumor-bearing mice concomitantly with intratumoral AdCD40L. End points measured included the frequencies of cytotoxic T lymphocytes using the enzyme-linked immunospot assay, tumor size, and mouse survival. The role of class I expression was further evaluated by monoclonal antibody blockade in both in vitro and in vivo experiments. RESULTS: B16.F10 cells exposed to interferon-gamma expressed significantly more class I, both in vitro and in vivo, and were able to bind to and activate cytotoxic T lymphocytes more efficiently than untreated cells. Cytotoxic T-lymphocyte frequencies, tumor regression, and the cure rate induced by AdCD40L were augmented by the addition of a single dose of interferon-gamma in tumor-bearing mice. These in vitro and in vivo effects of interferon-gamma were attenuated by class I monoclonal antibody blockade. CONCLUSIONS: Up-regulation of class I expression using interferon-gamma enhances the cellular antitumor immune response and cure rate of AdCD40L, an active immunotherapy strategy. This approach may be useful for human tumors that lack class I expression.
DOI	10.1016/j.jtcvs.2003.09.007
PubMed ID	14762342