Presence or absence of melanocytes in vitiligo lesions: An immunohistochemical investigation

There is a long-standing controversy over whether melanocytes in vitiligo lesions are actually lost or are still present but inactivated. Resolving this matter is essential for understanding the underlying pathology and for the development of treatment. Standard methods of detecting melanocytes are based on active melanin synthesis. However, it is possible that inactive melanocytes remain in the lesions. There are no methods presently available to detect such dormant melanocytes. Using a panel of one polyclonal and 17 monoclonal antibodies directed against melanocytic cells (largely selected by the European Organisation for Research and Treatment of Cancer Melanoma Group for diagnostic and therapeutic purposes), we investigated the absence or inactivation of melanocytes in vitiligo by immunohistochemistry. Results using this panel of antibodies on frozen skin sections suggest that melanocytes are indeed absent in the lesions. However, in epidermal split-skin preparations, residual staining was occasionally observed. To determine whether the staining obtained was due to degenerated melanocytes, confocal laser scanning microscopy was used. Immunofluorescent staining using the antibody NKI-beteb confirmed this to be the case. The results presented here strongly suggest that melanocytes are indeed lost in vitiligo lesions.