Immunology USMLE Step 1 Practice Question
A 6-year-old boy with sickle cell disease presents with fever (39.2°C), lethargy, and nuchal rigidity. Vital signs show HR 128/min, RR 28/min, BP 102/68 mmHg, and SpO2 98% on room air. Blood cultures grow an encapsulated gram-positive diplococcus that is alpha-hemolytic and optochin-sensitive. CSF shows elevated protein at 180 mg/dL. He denies recent head trauma. Functional loss of which splenic role most likely predisposed this patient to severe meningococcal infection?
Answer choices
- AClass switching of B cells from IgM to IgG
- BGeneration of neutrophils from myeloid precursors
- CProduction of erythropoietin
- DMaturation of T lymphocytes
- ERemoval of opsonized encapsulated bacteria from bloodCorrect answer
- FProduction of tuftsin and other opsonins that coat encapsulated bacteria
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