A 5-year-old boy develops daily spiking fevers for 3 weeks with return to normal or subnormal temperatures between spikes. He has a salmon-colored evanescent rash during fever, hepatosplenomegaly, lymphadenopathy, and arthritis of the knees. Ferritin is 18,000 ng/mL. Which cytokine is most responsible for the pathogenesis of this condition?

• A IL-1β, IL-6, and IL-18 (inflammasome-mediated) ✓
• B IL-4 and IL-13 (Th2 cytokines)
• C TNF-alpha and IFN-gamma
• D IL-17A and IL-22 (Th17 pathway)

Explanation

Systemic juvenile idiopathic arthritis (sJIA, Still's disease) is an autoinflammatory (not autoimmune) disease with hallmark features of quotidian (daily spiking) fevers, salmon-colored rash, arthritis, and organomegaly. Markedly elevated ferritin (>10,000) is a red flag for macrophage activation syndrome (MAS), a life-threatening complication. sJIA pathogenesis is driven primarily by the IL-1 and IL-6 pathways (innate immunity/inflammasome activation) rather than adaptive immunity. IL-1β, IL-6, and IL-18 are the key cytokines. This is why IL-1 antagonists (anakinra, canakinumab) and IL-6 receptor antagonists (tocilizumab) are highly effective targeted therapies for sJIA.

Reference: Ghai Essential Pediatrics, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.