The results revealed that naïve CD4+ T cells from patients with active BD, when cultured under Th17 polarizing conditions, showed a significantly higher frequency of IL-17-producing CD4+ T cells in patients with active BD (25.8 ± 6.4) than did naïve CD4+ T cells from patients with inactive BD (10.2 ± 2.3; P = 0.048) or healthy controls (9.6 ± 2.6; P = 0.024). This evidence concerns the gene IL17A and Behcet disease.