Shining light on lupus and UV

People exposed to sunlight can develop erythema, DNA damage, and photoimmunosupression. Extended exposure of normal epidermis to sunlight will induce dysmorphic keratinocytes with pyknotic nuclei scattered throughout the spinous layer. These 'sunburn cells' are apoptotic keratinocytes and are usually cleared within 48 hours after sunburn. Patients with lupus erythematosus, however, whether it be the discoid, subacute cutaneous, systemic, or tumid form, develop new cutaneous lesions and can experience systemic worsening of their disease. Are sunlight-induced keratinocyte apoptosis and the immune response to these cells abnormal in lupus patients?