8-Methoxypsoralen-DNA Adducts in Patients Treated with 8-Methoxypsoralen and Ultraviolet A Light

The combination of 8-methoxypsoralen (8-MOP) plus ultraviolet A light (320–400nm), termed PUVA, is used in the treatment of psoriasis, a hyperproliferative disease of the skin. This treatment results in the formation of specific 8-MOP adducts with cellular DNA. We have previously developed monoclonal antibodies which recognize these 8-MOP photoadducts. We now report the use of these antibodies in an indirect immunofluorescence technique to study human skin biopsies. Nuclei in 3 of 5 skin biopsies from psoriasis patients undergoing PUVA therapy were positive for adducts. The presence of adducts by immunofluorescence did not correlate with plasma levels of 8-MOP. Enzyme-linked immunosorbent assays, used to determine whether 8-MOP photoadducts could be detected in DNA isolated from the lymphocytes of psoriasis patients after PUVA therapy, were negative.