Immunology USMLE Step 1 Practice Question
A 2-year-old male presents with fever (39.2°C), tachypnea (RR 48/min), and hypoxia (SpO2 88%) with pneumonia caused by Streptococcus pneumoniae. Since age 6 months, he has experienced recurrent pneumonia and sinusitis from encapsulated bacteria despite appropriate antibiotic therapy. Physical examination reveals no lymphadenopathy. Chest X-ray confirms left lower lobe infiltrate. Immunological assessment would most likely demonstrate dysfunction of which immune component?
Answer choices
- AT lymphocytes
- BB lymphocytesCorrect answer
- CNatural killer cells
- DPlatelets
- EMacrophages
- FComplement system
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