Immunology USMLE Step 1 Practice Question
A 52-year-old man presents with fever (38.5°C), malaise, and cough for 3 days. Viral PCR is positive. Physical examination reveals decreased breath sounds bilaterally; chest X-ray shows bilateral infiltrates. Laboratory studies demonstrate markedly downregulated class I MHC molecules on infected respiratory epithelial cells. White blood cell count is normal. He denies recent antibiotic use. Which immune cell is best able to recognize and kill these infected cells early in infection?
Answer choices
- ACD8 positive cytotoxic T lymphocytes
- BPlasma cells
- CB lymphocytes
- DNatural killer cellsCorrect answer
- EEosinophils
- FCD4+ helper T cells recognizing viral peptides on MHC class II
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