Background Interleukin-17 (IL-17) has been associated with the pathogenesis of numerous autoimmune/inflammatory diseases. The aim of our study was to investigate the expression of Th17-related immunity in two phenotypically different disorders: Behcet's disease (BD) with innate and Takayasu's arteritis (TAK) with adaptive immune responses.

Methods Peripheral blood mononuclear cells (PBMC) from 32 patients (age: 39.2±10.1 years) with BD, 13 patients (age: 50.9±15.5 years) with TAK and 18 HC (age: 40.9±6.9 years) were cultured in Th17 inducing condition (IL-6, PHA, IL-1beta and IL-23) for 6 days. Cultured cells were stained with CD4, CD8, CD3, TCRgamma/delta, CD19, IFN-g and IL-17 antibodies to determine the intracellular cytokine secretion by flow cytometry.

Results In BD patients, IL-17 expression by CD4 T cells was observed to be higher than both TAK patients and HC (p=0.03 and p=0.02, respectively). IL-17 expression by gamma delta and CD8 T cells was also higher in BD compared to HC (p=0.03, p<0.01 respectively). No differences were observed between the groups in the IL-17 production by B cells. Under Th17 inducing condition, production of IFN-g by CD4 and CD8 T cells were also higher in both BD and TAK patients compared to the HC (p<0.05 in all). No differences were observed between the groups in IFNg production by B cells and gamma/delta T cells.

Conclusions Our preliminary results suggest that under Th17 stimulating condition, T cells express higher IL-17 levels in BD. More prominent IL-17 and IFN-g production by all lymphocyte subsets in BD might be associated with the increased innate responses and early tissue neutrophil infiltrations in BD, which is not observed in TAK.

Disclosure of Interest None declared