Interleukin-8 immunoreactivity in malignant tumours of the skin.

In the past, interleukin-8 (IL-8) could be demonstrated within keratinocytes in normal epidermis and inflammatory skin diseases, like psoriasis and eczema. Using monoclonal antibodies, the distribution of IL-8 immunoreactivity was inversely related to the density of inflammatory infiltrate. Other in vitro observations indicated IL-8 to be a growth factor for keratinocytes. These results prompted an immunohistochemical examination of IL-8 immunoreactivity in malignant and semimalignant epithelial tumours of human skin. Whereas IL-8 could not be detected within the transformed cells of epithelial tumours or melanoma, some tumour cells within well differentiated squamous cell carcinoma and Bowen's disease showed IL-8 immunoreactivity. Thus, loss of IL-8 immunoreactivity can be a sign of malignant transformation. This indicates an important role in growth regulation as well as terminal differentiation of human keratinocytes.