Inflammation and Immune Pathology USMLE Step 1 Practice Question
A 19-year-old male college student presents to the emergency department with a 12-hour history of fever (39.2°C), severe pharyngitis, and a rapidly progressive petechial rash beginning on the neck and spreading to the trunk. On examination, he is tachycardic (HR 118/min), hypotensive (BP 92/58 mmHg), and tachypneic (RR 22/min). Notably, he has no neck stiffness or positive Kernig sign. Lumbar puncture reveals cerebrospinal fluid with 850 WBC/μL (predominantly neutrophils), protein 180 mg/dL, and glucose 35 mg/dL. Blood culture grows gram-negative diplococci. Which of the following best explains the pathophysiologic mechanism underlying this patient's acute shock and multi-organ inflammation?
Answer choices
- ABacterial lipopolysaccharide binding to TLR4 on macrophages and dendritic cells, triggering NF-κB activation and massive release of TNF-α and IL-1βCorrect answer
- BCross-linking of IgE on mast cell surfaces by bacterial antigens, triggering degranulation and immediate hypersensitivity responses
- CBacterial peptidoglycan fragments activating the contact system cascade leading to unchecked thrombin generation
- DDirect bacterial invasion of vascular endothelium causing physical disruption of the blood-brain barrier
- EComplement-mediated opsonization of bacteria by IgM and classical pathway activation alone without innate immune participation
- FT helper type 17 differentiation and IL-17 production as the primary driver of neutrophil recruitment and tissue damage
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