Differences in Reactivity to Cyclosporin A and Interferon-gamma of Normal and HPV-transformed Keratinocytes

In humans, cyclosporin A (CsA) avoids organ allograft rejection but induces skin carcinomas after long term immunosuppressive treatment; some of these lesions contain human papillomavirus (HPV) DNA. Interferon-gamma (IFN-gamma) is sometimes used in local treatment of persistent or recurrent lesions in normal population. In vivo, both drugs have an effect on keratinocytes which remains unclear. Therefore, their effect was studied on in vitro models of normal or HPV-transformed epithelial cell cultures. After exposure of proliferating cells for 1-3 days to 0.5-16 micrograms/ml CsA and 5-160 U/ml IFN-gamma, no cytotoxicity was observed; cell growth was inhibited; cell morphology was altered with CsA and cytoplasmic vacuoles were seen in some cells. Changes in the cell cycle were mainly obtained after treatment with 8 micrograms/ml CsA or 160 U/ml IFN-gamma, with an accumulation in S-phase especially in HPV-transformed cells. Thus, CsA and IFN-gamma affected, normal and HPV-transformed epithelial cells, differently.