DNA repair synthesis in human skin exposed to ultraviolet radiation used in PUVA (psoralen and UV-A) therapy for psoriasis.

The ultraviolet radiation used for PUVA therapy stimulated DNA repair activity in normal human skin and in the uninvolved skin from psoriatic patients. The activity detected by autoradiography increased linearly with exposure time. No stimulation was observed when the UV-B component was removed from the incident radiation by filtration through glass. Therefore UV-B damage to DNA was found responsible for the activity detected following exposure to the unfiltered PUVA light source.