TNF and familial Mediterranean fever: Indeed, at the serum level, pro-inflammatory cytokines IL-6, IL-12, IL-17, IL-18, soluble IL-2 receptor (sIL-2R), interferon-gamma (IFN-γ), and tumor necrosis factor alpha (TNF-α) were reported to be higher in FMF patients during or between attacks than in healthy controls, supporting the ongoing subclinical inflammation in FMF (35).