CD4 and Behcet disease: Although the exact mechanism of vasculo-BD is not fully understood, since immunological cells including neutrophils and mononuclear cells (predominantly CD3+CD4+ T lymphocytes and NK cells) infiltrate into the media and adventitia of arterial wall, dysregulated expression of proinflammatory mediators such as TNF-α, interleukin- (IL-) 1β, IL-6, and IL-17 may be involved in the pathogenesis of vasculo-BD [11].