Bacterial Infections USMLE Step 1 Practice Question
A 42 year old man recently immigrated from a high prevalence country and presents with months of cough, weight loss, evening fevers, and night sweats. Chest radiograph shows upper lobe cavitary lesions. Sputum acid fast stain is positive. Which of the following immunologic mechanisms is most responsible for the characteristic tissue injury seen in this disease?
Answer choices
- AType IV hypersensitivity mediated by Th1 cells and activated macrophagesCorrect answer
- BType II hypersensitivity mediated by IgG against basement membrane
- CType III hypersensitivity mediated by circulating immune complexes
- DType I hypersensitivity mediated by IgE
- EComplement mediated neutrophil chemotaxis from endotoxin release
- FType II hypersensitivity mediated by IgM antibodies against mycobacterial surface antigens
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