Inflammation and Immune Pathology USMLE Step 1 Practice Question
A 34-year-old woman presents with fever (38.5°C), polyarthralgias, and a photosensitive malar rash. Vital signs show BP 128/82 mmHg, HR 92/min, RR 16/min, SpO2 98% on room air. Labs reveal positive ANA (1:640) and anti-dsDNA antibodies; urinalysis shows mild proteinuria (0.8 g/24 hr) with normal creatinine (0.9 mg/dL). Renal biopsy demonstrates subendothelial immune complex deposition. She denies prior renal disease. Which pathologic mechanism best explains her glomerulonephritis?
Answer choices
- ADirect antibody binding to glomerular epitope
- BT cell-mediated cytotoxicity of podocytes
- CNeutrophil elastase degradation of collagen IV
- DImmune complex deposition in the basement membraneCorrect answer
- EComplement-mediated cell lysis without antibody involvement
- FCirculating anti-GBM antibodies cross-linking with planted antigens
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