Inflammation and Immune Pathology USMLE Step 1 Practice Question
A 34-year-old man with recent streptococcal pharyngitis develops two weeks of progressive dyspnea, orthopnea, and lower extremity edema. Echocardiography shows a dilated left ventricle with reduced ejection fraction. Serum creatinine is elevated, and urinalysis shows RBC casts and mild proteinuria. Which of the following immune mechanisms best explains the cardiac and renal pathology?
Answer choices
- AIgE-mediated type 1 hypersensitivity causing systemic anaphylaxis
- BMassive complement activation from immune complex deposition causing acute myocarditis
- CMolecular mimicry of streptococcal antigens cross-reacting with myocardial and glomerular basement membrane proteinsCorrect answer
- DTh1-mediated granulomatous inflammation in the myocardium
- EPersistent streptococcal superantigen activation of all T cells regardless of specificity
- FDirect bacterial invasion of cardiac myocytes and glomeruli by nephritogenic streptococcal strains
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