Abstract
Impaired immune responses occur frequently in cancer patients or in tumor-bearing mice, but the mechanisms of the tumor-induced immune defects remain poorly understood. In an in vivo murine colon carcinoma model (MCA-38), animals bearing a tumor longer than 26 days develop CD8+ T cells with impaired cytotoxic function, decreased expression of the tumor necrosis factor-alpha and granzyme B genes, and decreased ability to mediate an antitumor response in vivo. T lymphocytes from tumor-bearing mice expressed T cell antigen receptors that contained low amounts of CD3 gamma and completely lacked CD3 zeta, which was replaced by the Fc epsilon gamma-chain. Expression of the tyrosine kinases p56lck and p59fyn was also reduced. These changes could be the basis of immune defects in tumor-bearing hosts.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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CD3 Complex / metabolism
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CD8 Antigens / analysis
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Calcium / metabolism
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Colonic Neoplasms / immunology*
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Cytotoxicity, Immunologic*
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Granzymes
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Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
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Macromolecular Substances
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Mice
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Protein-Tyrosine Kinases / metabolism
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-fyn
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Receptors, Antigen, T-Cell / isolation & purification
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Receptors, Antigen, T-Cell / metabolism
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Receptors, IgG / metabolism
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Serine Endopeptidases / biosynthesis
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Serine Endopeptidases / genetics
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Signal Transduction*
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T-Lymphocyte Subsets / immunology
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T-Lymphocytes / immunology*
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T-Lymphocytes / physiology
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Tumor Necrosis Factor-alpha / biosynthesis
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Tumor Necrosis Factor-alpha / genetics
Substances
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CD3 Complex
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CD8 Antigens
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Macromolecular Substances
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Proto-Oncogene Proteins
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Receptors, Antigen, T-Cell
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Receptors, IgG
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Tumor Necrosis Factor-alpha
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Protein-Tyrosine Kinases
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Fyn protein, mouse
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Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
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Proto-Oncogene Proteins c-fyn
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Granzymes
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Gzmb protein, mouse
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Serine Endopeptidases
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Calcium