S100A8/A9 (Calprotectin)
Alarmin and DAMP released by activated phagocytes; amplifies TLR4 signaling
- Expression
- Elevated
- Evidence level
- moderate
Role in pathogenesis
Calprotectin (S100A8/A9 heterodimer) is released by activated neutrophils and macrophages. It activates TLR4 signaling, further stimulating the innate immune cascade. Serum calprotectin is significantly elevated in active AOSD, correlates with disease activity and severity, and decreases after treatment. Serves as a promising disease activity biomarker.