What's new in photoimmunology?

The immunosuppression that follows exposure to ultraviolet radiation (UVR) is generated by complex multistep pathways that have been only partially elucidated. The process starts with cutaneous chromophores and most likely ends with the amplification of subsets of T-regulatory cells. Considerable efforts have been made to identify the roles of Langerhans cells and keratinocytes, located in the epidermis, and dendritic cells and macrophages, located in the dermis, in this cascade. Less attention, by comparison, has been paid to mast cells.