Inflammation and Immune Pathology USMLE Step 1 Practice Question
A 62-year-old man with a history of chronic hepatitis C develops jaundice, rash on the lower extremities, and glomerulonephritis with RBC casts in the urine. Serum cryoglobulins are elevated, and complement levels (C3, C4) are low. Which of the following immune mechanisms is responsible for the vasculitis and glomerulonephritis in this patient?
Answer choices
- AType IV hypersensitivity: Th1-mediated vasculitis with granuloma formation
- BType I hypersensitivity: mast cell degranulation causing vessel permeability
- CType II hypersensitivity: antibody binding to viral antigens on vessel walls
- DType III hypersensitivity: immune complex deposition with complement activationCorrect answer
- EAntibody-mediated complement-independent destruction of endothelial cells
- FType II hypersensitivity: direct IgM antibody binding to basement membrane antigens
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