General Pathology USMLE Step 1 Practice Question
A 2-year-old boy presents with recurrent skin and mucosal bacterial infections, delayed umbilical cord separation at 6 weeks of life, and fever (38.5°C). Vital signs show HR 110/min, RR 28/min, BP 95/62 mmHg. Laboratory studies reveal WBC 18,500/μL with marked neutrophilia. Despite purulent infection, minimal pus forms at infected sites. Flow cytometry demonstrates absent CD18 expression on neutrophils. Which step of the acute inflammatory response is primarily impaired?
Answer choices
- APhagolysosome fusion
- BGeneration of reactive oxygen species
- CRolling mediated by selectins
- DOpsonization by IgG and C3b
- EFirm adhesion of neutrophils to endotheliumCorrect answer
- FChemotaxis along a concentration gradient of bacterial products
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