In healthy skin (left), UV light generates an immunosuppressive environment characterized by efficient clearance of apoptotic cells, immune cell activation, and secretion of protective/suppressive cytokines including type I interferons (IFNs) and IL-10. In lupus skin, UV light exposure is inflammatory secondary to increased immune cell infiltration, inhibition of negative regulatory mechanisms, and amplified production of type I IFNs that enhance keratinocyte apoptosis. Apoptotic cells are not efficiently cleared resulting in increased autoantigen exposure, immune complex formation, and lesion development.