The role of regulatory T cells in familial Mediterranean fever (FMF).

The role of regulatory T cells (T-regs) in familial Mediterranean fever (FMF) was never evaluated. Preliminary studies that we have conducted suggested a rise in the number of regulatory T cells after FMF attacks reaching a maximal level at 7 days. The aim of this study was to evaluate the percentage and activity of regulatory T cells in FMF. Six patients with refractory FMF and six healthy controls were evaluated. The percentage of T-reg cells and forkhead box protein 3 (Foxp3) expression was evaluated and compared between four states: FMF in remission, FMF at the first day of an attack, FMF 7 days after the start of the attack, and healthy controls. Four females and two males were included. All patients had FMF with high severity score, 2.8 ± 0.4 (0-3). The mean age was 31.6 ± 6.2. The mean age at onset was 9.3 ± 9.3. The mean colchicine dose was 2.6 mg ± 0.4. The expression of Foxp3 7 days after the attacks was significantly higher than in FMF at the first day of the attack, FMF in remission, and healthy controls 10.08 ± 2.36 vs. 7.005 ± 0.3 vs. 5.3 ± 1.06 vs. 4.44 ± 1.8; p < 0.05 (Fig.1). The percentage of T-regs in peripheral blood was not statistically different between the four groups. Theexpression of Foxp3 by T-regs increases 7 days after attacks of FMF. Anti-inflammatory cytokines interleukin-10 and TGF-β are known to activate T-regs and have been reported to increase in FMF attacks in line with the present findings. It is suggested that T-regs may have a role in terminating FMF attacks.