Podcast
Questions and Answers
Which of the following mechanisms is NOT a way that malignant tumors evade host immune responses?
Which of the following mechanisms is NOT a way that malignant tumors evade host immune responses?
- Down-regulation of class I MHC expression on tumor cells
- Production of tumor cell products that suppress anti-tumor immune responses
- Induction of specific immunologic tolerance by tumor antigens
- Expression of costimulators and class II MHC molecules on tumor cells (correct)
How can the downregulation of class I MHC expression on tumor cells help them evade the immune system?
How can the downregulation of class I MHC expression on tumor cells help them evade the immune system?
- It prevents the tumor cells from being recognized by natural killer (NK) cells.
- It prevents the tumor cells from activating the complement pathway.
- It prevents the tumor cells from being recognized by cytotoxic T lymphocytes (CTLs). (correct)
- It prevents the tumor cells from expressing tumor-associated antigens.
How can the loss of expression of antigens that elicit immune responses help malignant tumors evade the immune system?
How can the loss of expression of antigens that elicit immune responses help malignant tumors evade the immune system?
- It prevents the tumor cells from expressing costimulators and class II MHC molecules.
- It prevents the tumor cells from being recognized by cytotoxic T lymphocytes (CTLs). (correct)
- It prevents the tumor cells from activating the complement pathway.
- It prevents the tumor cells from being recognized by natural killer (NK) cells.
What role do costimulators and class II MHC molecules play in immune response to tumors?
What role do costimulators and class II MHC molecules play in immune response to tumors?
How can the products of tumor cells suppress anti-tumor immune responses?
How can the products of tumor cells suppress anti-tumor immune responses?
Flashcards
MHC Class I Downregulation
MHC Class I Downregulation
Tumor cells can evade CTLs by reducing their expression of MHC Class I, making it difficult for CTLs to recognize them.
Loss of Tumor Antigens
Loss of Tumor Antigens
Tumors may become invisible to the immune system by losing the antigens that prompt an immune response.
Lack of Costimulatory Signals
Lack of Costimulatory Signals
Tumors can avoid triggering CTLs by failing to express the necessary signals (costimulators and MHC Class II) for proper activation.
Tumor-Derived Immune Suppression
Tumor-Derived Immune Suppression
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Immunologic Tolerance to Tumor Antigens
Immunologic Tolerance to Tumor Antigens
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Study Notes
Immune Evasion Mechanisms in Malignant Tumors
- Malignant tumors often evade or resist the host's immune system.
- Reduced Class I MHC expression: Tumor cells may downregulate Class I MHC molecules, preventing cytotoxic T lymphocytes (CTLs) from recognizing and attacking them.
- Loss of immunogenic antigens: Tumors may lose the expression of antigens that would normally trigger an immune response.
- Lack of costimulators and Class II MHC: Tumor cells often fail to express costimulators or Class II MHC molecules, hindering the activation and differentiation of CTLs.
- Immunosuppressive tumor products: Tumor cells can produce substances that suppress anti-tumor immune responses.
- Induced immunologic tolerance: Tumor antigens can sometimes induce specific immunological tolerance, making the system less able to fight the tumor.
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