Immunohistochemical study of granulysin expression in vitiligo and halo nevus

Abstract Vitiligo and halo nevus are immune-mediated skin diseases that have a similar pathogenesis and involve cellular cytotoxicity mechanisms that are not yet fully understood. In this study, we investigated whether cytotoxic cells containing cytolytic molecules such as granulysin (GNLY) are present in lesions of vitiligo and halo nevus. We analysed the expression of GNLY by immunohistochemistry in different lymphocyte subsets in perilesional and lesional skin of ten vitiligo patients, eight patients with halo nevus and ten healthy controls. A significantly higher accumulation of GNLY+, CD8+ GNLY+ and fewer CD56+ GNLY+ cells was found in the lesional skin of vitiligo and halo nevus than in the healthy skin. These cells were localised in the basal epidermis and papillary dermis, suggesting that GNLY may be involved in the immune response against melanocytes. Similarly, but to a lesser extent, upregulation of GNLY+ and CD8+ GNLY+ cells was observed in the perilesional skin of vitiligo and halo nevus compared to healthy controls. In this study, we demonstrated, for the first time, increased expression of CD8+ GNLY+ T lymphocytes and CD56+ GNLY+ NK cells in lesions of vitiligo and halo nevus, indicating the role of GNLY-mediated cytotoxicity in the development of both diseases.