Common links among the pathways leading to UV-induced immunosuppression.

In this issue, Sreevidya et al. demonstrate unexpected similarities in the downstream events of two molecular triggers of UV-induced immunosuppression. Both platelet-activating factor and cis-urocanic acid produced reactive oxygen species (ROS). Blocking both photoproducts reduced UV-induced genetic damage. Vitamin D, another immunosuppressive photoproduct, does not share this property but instead enhances DNA repair. This study therefore links ROS and genetic damage with two molecular triggers of UV immunosuppression.