Lack of association between serum IL-9 levels and Behçet's disease.

INTRODUCTION: Considering the role of interleukin (IL)-9 and IL-9-producing Th9 cells in pathogenesis of autoimmune diseases, this study aimed to evaluate serum IL-9 levels in patients with Behçet's disease (BD) compared to healthy subjects and to assess whether there is an association between serum IL-9 levels and disease characteristics in BD.

METHODOLOGY: In this cross-sectional study, 32 BD patients according to the International Criteria for BD (ICBD) and 56 age-matched healthy controls were included. In patients, clinical examination was performed and Behcet's Disease Current Activity Form (BDCAF), Iranian Behcet's Disease Dynamic Activity Measure (IBDDAM) and Total Inflammatory Activity Index (TIAI) were assessed. Serum IL-9 level was measured using ELISA kit.

RESULTS: The mean ± SD age of patients and controls was 39.06 ± 9.86 and 38.64 ± 8.40 years, respectively and 41% of patients and 66% of controls were males. The most common clinical symptoms in BD patients were oral aphthous ulcers, ocular involvement, and genital ulcers, respectively. The median (Min-Max) of BDCAF, IBDDAM and TIAI in patients were 2 (0-4), 1.3 (0-7), and 2 (0-22), respectively. There was no significant difference in serum IL-9 levels between BD patients (47.12 ± 7.34 mg/dL) and healthy controls (48.61 ± 7.76 mg/dL) (P > 0.05). There were no significant correlations between serum IL-9 levels with BD clinical characteristics as well as with disease severity (P > 0.05).

CONCLUSION: Our study revealed no significant difference in serum IL-9 between BD patients and healthy controls as well as no significant correlation between serum IL-9 with clinical characteristics and disease severity. Further studies are certainly needed, but on a wider cohort of BD patients to identify IL-9 involvement in BD pathogenesis.