Granulysin-producing cytotoxic T cells in the mucocutaneous lesions of Behçet disease: A distinct inflammatory response from erythema nodosum

Background. Cytotoxic T lymphocytes (CTLs) have been recognized as an important effector cell in Behçet disease (BD). Granulysin is a cytolytic granule protein expressed by CTLs and natural killer cells. Aim. To evaluate the involvement of granulysin-producing T cells in the pathogenesis of BD. Methods. Using immunohistochemistry, lymphocyte subsets expressing granulysin were investigated in mucocutaneous lesions of BD. Serum granulysin levels were assayed by ELISA. Results. Granulysin-positive cells were seen in specimens from oral ulcers, genital ulcers and acne-like eruptions, but not erythema nodosum-like lesions. Both CD4+ and CD8+ T cells expressed granulysin. Serum granulysin levels did not correlate with disease activity in BD. Conclusion. Immune reactions mediated by granulysin-positive CTLs may play an important role in the pathogenesis of acne-like eruptions, oral ulcers and genital ulcers in BD.