NK Cells Can Be Activated Following Recognition of a Virus-Infected

question 31

Multiple Choice

NK cells can be activated following recognition of a virus-infected cell, if that cell has down-regulated expression of MHC class I proteins on its surface. However, NK cells can also recognize infected cells or tumor cells, even if they still express MHC class I proteins. In this latter case, activating receptors on NK cells are recognizing:

• A) Molecules on the target cell up-regulated by cellular or metabolic stress
• B) Cytokines secreted by the virus-infected or tumor cell
• C) MHC class I-like decoy molecules encoded by the virus
• D) Mutated self-proteins expressed by the tumor cell
• E) Double-stranded DNA in the cytoplasm of the infected or tumor cell

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