Dysregulated mature IL-1β production in familial Mediterranean fever.
The aim of this study was to analyse the role of circulating cleaved IL-1β in patients with FMF. We enrolled 20 patients with FMF (5 males and 15 females), 22 patients with RA (4 males and 18 females) and 22 healthy controls (6 males and 16 females). Serum levels of serum amyloid A (SAA) were measured by ELISA. We also determined whether IL-1β was present as the cleaved form (p17) in the sera of FMF patients by immunoblotting using anti-cleaved IL-1β antibody. Although SAA concentrations were elevated in the sera, there was no significant difference in these concentrations between FMF patients and RA patients. Immunoblot analysis demonstrated that the cleaved form of IL-1β (p17) was present in sera from FMF patients during febrile attack periods, but not in healthy controls. Bands representing the cleaved form of IL-1β were not detected in serum from FMF patients at non-febrile attack periods or remission periods under colchicine treatment. The amounts of cleaved IL-1β (p17) were significantly higher in patients with FMF compared with those in patients with RA in the inflammatory phase. The cleaved form of IL-1β is a valuable biomarker for monitoring disease activity and response to colchicine treatment in patients with FMF. It might be useful to discriminate FMF from other non-IL-1β-mediated inflammatory disorders.