Immunology USMLE Step 1 Practice Question
A 19-year-old college student presents with fever (39.8°C), headache, and nuchal rigidity. He was hospitalized twice within one year for meningococcal meningitis confirmed by CSF culture and Gram stain showing gram-negative diplococci. Vital signs: BP 118/76, HR 102, RR 20, SpO2 98% on room air. He denies recurrent sinopulmonary infections. Family history is significant for a brother with meningococcal disease. He takes no immunosuppressive medications. Deficiency of which complement component most likely explains his recurrent infections?
Answer choices
- AC1 esterase inhibitor
- BMannose binding lectin
- CFactor H
- DC5 through C9Correct answer
- EC3
- FProperdin deficiency
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