Given that CD6 is required for optimal immune response, it is not surprising that many studies have linked CD6 with the pathogenesis of human autoimmune disease, such as Behcet’s disease (23), multiple sclerosis (MS) (24, 25), psoriasis (26), Sjögren’s syndrome (27, 28), rheumatoid arthritis (RA) (29), uveitis (30), inflammatory bowel disease (31), and most recently, lupus nephritis (32). Here, CD6 is linked to Behcet disease.