Investigation into Tc17 cell activation confirmed that CD8 + T cells are infiltrated in peripheral vascular walls and the subcutis in BD, and, concurrently, IL-17A + CD8 + T cells were elevated in BD compared to psoriasis vulgaris lesions and were a major source of IL-17A rather than CD4 + T cells (65). This evidence concerns the gene CD8A and Behcet disease.