Increased circulating Th17 frequency is correlated with Behçet’s diseases (BD) activity. (A): Representative figures of Th17 cells from a normal control and one active BD patient. CD4+IL-17+ Th17 were gated from CD3+ T cells. (B): Percentage of Th17/CD4+ cells from 45 active BD patients, 28 remission BD patients, 40 healthy controls (HC), 12 multiple sclerosis (MS) and 20 systemic lupus erythematosus (SLE) patients. The frequencies of Th17 cells in active BD patients and all two patient groups are significantly higher than for normal controls and remission BD patients. The medians are indicated by a line inside each box, the 25th and 75th percentiles by the box limits, the lower and upper error bars represent the 10th and 90th percentiles. (C1): Histologic feature of middle dermis of erythema nodosum (EN)-like eruption taken from active BD patient. Mononuclear cells are mainly infiltrated around and in the walls of vessels in the middle dermis (HE, 200×) [30]. Panels on the right show immunochemical histology of the EN-like eruption with a predominance of CD3+ lymphocytes around vessels. (C2): Lesional skin was further stained with IL-17. Bars =100 μm.