CD8A and Behcet disease: To determine whether the clinical benefit of phototherapy in BD is related to improved CD8+ T‐cell control of EBV infection, the clinical effect of exposure to sunlight or artificial bright light could be correlated with any changes in the numbers of total CD8+ T cells, CD8+ EM T cells and CD8+ EMRA T cells and with any changes in the CD8+ T‐cell response to EBV after phototherapy.