Why is polymorphous light eruption so common in young women?

Despite the fact that polymorphous light eruption (PLE) is the most common photodermatosis, affecting 15% of healthy people in the UK, its pathogeny remains unclear. The condition is more frequent in females and begins often in young adults and in mid-adult life. The mechanism of PLE is under active research as shown by recent results, and it is hypothesized that in PLE patients, there is a partial failure of ultraviolet radiation-induced immunosuppression, causing an abnormal response to autologous antigens generated by ultraviolet radiation (UVR). The recent demonstration that the female hormone, 17beta-estradiol prevents UVR-induced suppression of the contact hypersensitivity response caused by the release of immunosuppressive cytokines (IL-10) from keratinocytes might thus explain why the risk of PLE is higher in females than in males and why the risk decreases in women after the menopause.