High-performance liquid chromotography analysis of 8-methoxypsoralen monoadducts and crosslinks in lymphocytes and keratinocytes.

Human lymphocytes and murine keratinocytes were treated with clinically relevant doses of 8-methoxypsoralen and long-wavelength ultraviolet radiation. The extent of 8-MOP photoadduct formation was determined by liquid scintillation analysis. The distribution of photoadducts was determined by HPLC analysis of enzymatically hydrolyzed DNA from these cells. Analysis of photoadduct formation in lymphocytes and keratinocytes showed that 4',5'-monoadducts were the predominant photoadducts (42% and 41%, respectively). Monoadduct and crosslink yields were dependent on cell type as well as irradiating wavelength. The photochemical conversion of 400 nm-induced 4',5'-monoadducts to crosslinks, as well as 3,4-monoadducts in poly(dA-dT), was measured.