SAT0370 IMBALANCE OF TH17 AND REGULATORY T CELLS IN PATIENTS WITH PSORIATIC ARTHRITIS AND RE-BALANCE BY LOW-DOSE IL-2

Abstract

Background Psoriatic arthritis (PsA) is an T lymphocytes-mediated inflammatory condition [1]. Although regulatory T cells (Tregs) isolated from blood and psoriatic skin have been showed a functional deficiency in suppressing effector T-cells in PsA[2], absolute quantitative status of peripheral Treg or Th17 cells is still unclear. On the other hand, recent studies have revealed that low-dose IL-2 alleviates some of autoimmune disease activity by upregulating Treg cells [3,4], which is expected to control the development of PsA. Objectives To assess the absolute numbers of peripheral lymphocyte subpopulations and the efficacy and safety of low-dose IL-2 therapy in PsA patients. Methods Total 95 PsA patients and 106 age-and sex-matched healthy controls were recruited. Of them, 22 cases received the treatment of low-dose IL-2 at 0.5 million IU per day for 5 days subcutaneously. The absolute numbers of lymphocyte subgroups and CD4+T subsets in peripheral blood were measured by flow cytometry. The clinical manifestations and laboratory indicators as well as the levels of peripheral lymphocyte and CD4+T subsets were compared before and after the treatment. Results Notably, the absolute numbers of lymphocyte subpopulations in peripheral blood such as NK, CD4+T, Th17 and Tregs in PsA patients were lower than those of healthy controls (P Conclusion Patients with PsA had an imbalance between pro- and anti-inflammatory cells, particularly the reduction of the absolute number of Tregs. Low-dose IL-2 combination treatments restored the decreased number of Treg cells and lowered disease activity indicators of these patients without over-treatment and evaluable side effect. Further studies are needed to evaluate the long-term immunoregulatory ability of IL-2 treatment.