Immunology USMLE Step 1 Practice Question
A 46-year-old woman with metastatic breast cancer (HR 92, BP 128/82, SpO2 98% on room air) receives trastuzumab, a monoclonal antibody against HER2. Two months later, imaging shows 40% reduction in tumor burden. Laboratory studies reveal normal lymphocyte counts and negative infectious workup. She denies fever or constitutional symptoms. Which immune cell most directly mediates antibody-dependent cellular cytotoxicity against the antibody-coated malignant cells?
Answer choices
- ANeutrophils via CD18
- BEosinophils via major basic protein
- CMacrophages via CD14
- DNatural killer cells via CD16Correct answer
- ECytotoxic T cells via CD28
- FDendritic cells via CD40
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