IL6 and cryopyrin-associated periodic syndrome: As shown in Fig. 1, while an elevation in the level of IL-18 was observed in patients with CAPS when compared to the healthy controls (1366.1 ± 196.2 vs. 568.8 ± 171.9; p = 0.0008), the differences in levels of plasma IL-6 between CAPS and persistent sJIA were borderline significant (p = 0.051).