Six hours after a bee sting, the indurated lesion at the sting site is best explained by which process?

• A. Influx of macrophages producing IL-1, IL-6, and TNF-α
• B. Histamine-mediated vasodilation
• C. Lysis of endothelial cells by the alternative complement pathway
• D. Vasoconstriction

Answer: (A)

The indurated lesion six hours after a bee sting reflects the late inflammatory phase driven by macrophage activity. After the initial mast cell degranulation and histamine release causes immediate swelling, macrophages infiltrate the area and release proinflammatory cytokines like IL-1, IL-6, and TNF-α. These cytokines amplify inflammation, recruit more leukocytes, increase vascular permeability, and promote tissue changes that feel firm or indurated. The other options describe immediate histamine effects, complement-mediated endothelial damage, or vasoconstriction, which don’t explain the firm, cytokine-driven induration seen at this time point.