CD4 and Behcet disease: Our finding showing an enhanced expression of IL-22 in BD is in line with reports showing an increased IL-22 expression in serum, PBMCs or CD4+T cells in patients with psoriasis, RA, Crohn’s disease and primary Sjögren syndrome.[8]–[9], [12]–[13], [21]–[22] IL-22 has also been reported to be over-expressed in affected tissues of patients with these diseases, [6], [9]–[10], [23] which is similar to our finding showing an increased IL-22 mRNA expression in erythema nodosum skin lesions in BD patients.