Serum soluble interleukin-2 receptor levels in familial Mediterranean fever.

OBJECTIVE: To investigate serum soluble interleukin-2 receptor (sIL-2R) in familial Mediterranean fever (FMF) and assess its role in acute FMF crisis. METHODS: Serum sIL-2R concentrations were measured in patients with FMF during acute crises and during inactive periods of the disease, using an immunoenzymatic assay kit. Twenty four FMF patients during acute crisis (active FMF), 17 patients with inactive FMF, 24 healthy controls, and 20 active patients with rheumatoid arthritis (as a disease control group) were studied. RESULTS: Serum sIL-2R concentrations were increased during an acute FMF crisis compared with the values in inactive FMF patients and healthy controls (P = 0.0105 and P = 0.0012 respectively), while there was no significant difference between the mean values in active FMF and rheumatoid arthritis patients (P = 0.7325). In 14 of the FMF group whose blood samples were available in both active and inactive phases, sIL-2R concentrations were significantly higher in an acute attack than in an attack-free period (P = 0.027). CONCLUSIONS: An increase in sIL-2R may be a result of hyperreactivity of IL-2R-expressing cells during an acute inflammatory attack of FMF.