Background Recent studies have shown that increased number of Th17 cells and decreased number of Treg cells in the peripheral blood contribute to ankylosing spondylitis (AS). However, current therapy for AS, including biological agents, immunosuppressant and glucocorticoid, can not correct the imbalance of Th17 and Regulatory T (Treg) cells in AS patients effectively. It has been reported that low dose IL-2 can selectively expand Treg cells and had a critical effect on homeostatic balance between the Th17 and Treg cells.
Objectives The study is to explore the effect of low dose IL-2 therapy on the balance of Treg and Th17 cells in patients with AS and observe the efficiency and side effects of the therapy.
Methods Seventeen patients, who met the 1984 modified New York criteria and had evidence of active inflammatory spondylitis (defined as Bath AS Disease Activity Index (BASDAI) score >4) despite of receiving standard therapy including glucocorticoid, immune-suppressants, biological agents or combination of them, were enrolled. These patients were not only given traditional treatment, but also injected subcutaneously low-dose IL-2 (50 WIU/day for 5 days). Clinical and laboratory indicators were compared before and after IL-2 treatment. The side effects were observed in the course of therapy.
Results The number of Treg cells significantly increased after the treatment by 1 week (22.58±12.80 vs. 73.46±33.79, p<0.001). At the same time, there was a significantly decrease in the ratio of Th17/Treg cells (0.67±0.70 vs. 0.32±0.33, p=0.068). Besides, Th17 cells were also increased (12.83±9.24 vs. 19.26±13.24, p=0.054). Clinical manifestations were improved after the combination treatment of IL-2 and traditional drugs, especially BASDAI was decreased (4.57±0.61 vs. 1.98±0.83, P<0.001). No obvious adverse reactions were observed.
Conclusions Low dose IL-2 therapy can restore and maintain the balance of Th17 and Treg cells in the active patients with AS. Manifestation improved after the combination therapy. The therapy is safe. Further research is needed to investigate long term benefits of low-dose IL-2 therapy.
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Disclosure of Interest None declared