General Pathology USMLE Step 1 Practice Question
A 19-year-old college student presents with acute bacterial meningitis. Vital signs show BP 118/76 mmHg, HR 102 bpm, RR 22/min, temperature 39.2°C, and SpO2 98% on room air. CSF analysis reveals elevated protein (180 mg/dL) and positive gram stain. He denies recent antibiotic use. Inflammatory cytokines from activated macrophages upregulate adhesion molecules on local endothelial cells, enabling neutrophils to roll along vessel walls before migrating into tissue. Which molecule mediates this rolling step?
Answer choices
- AC3b binding to microbial surfaces
- BPECAM 1 between endothelial cells and leukocytes
- CCD40 ligand binding CD40 on macrophages
- DSelectins on endothelium binding sialyl Lewis X on leukocytesCorrect answer
- EIntegrins on neutrophils binding ICAM 1
- FComplement receptor 1 on neutrophils binding iC3b on endothelial cells
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