Cyclosporine

Cyclosporine, an immunosuppressant targeting CD4⁺ T lymphocytes, was found to directly affect the growth of various epithelial cell types. It stimulated hair follicle keratinocytes, causing hypertrichosis, while exerting a cytostatic effect on other epithelial cells. This antiproliferative effect was also observed in some cyclosporine analogues with minimal or no immunosuppressive properties, indicating different molecular mechanisms for epithelial cell growth modulation and immunosuppression. This discovery suggested potential for using nonimmunosuppressive cyclosporines in treating hyperproliferative epidermal diseases.