ABSTRACT
BACKGROUND: The Fas antigen is a cell surface molecule that mediates apoptosis in many cell types. Matsues group indicated that keratinocytes constitutively express the Fas antigen and apoptosis was induced only on pretreatment with interferon-r (IFN-y) in cultured normal human keratinocytes (NHK). OBJECTIVE: We undertook this study to determine the induction of apoptosis by Fas antibody alone and/or in combination with IFN y, IL-1a in normal human keratinocytes (NHK) and transitional epithelioma cell lines (KB cell) which had lower levels of intracellular IL-1 receptor antago- nists (IL-1ra ). METHODS: We used cultured NHK and KB cells. Each cell was treated with IFN-r, IL-la and Fas antibody for induction of apoptosis. For quantifying the apoptosis, index fluorescent DNA- binding dyes were used. Result: Fas antibody alone could induce apoptosis not only in KB cells but also in NHK cells. The combination of Fas antibody and IFN-r enhanced the induction of apoptosis in NHK and KB cells. The IL-la alone could induce apoptosis only in KB cells which had relatively small amounts of IL-1ra compared to NHK. CONCLUSION: Our result may indicate that Fas antigen in human keratinocytes can regulate normal epidermal cellular differentiation and proliferation.