Photochemical binding of photoallergens to human serum albumin: A simple in vitro method for screening potential photoallergens.

An in vitro screening procedure is described whereby potential photoallergens are irradiated with ultraviolet (UV) light in the presence of monomeric human serum albumin. UV spectroscopy before and after irradiation and after passage of the reaction mixture through Sephadex G-10, is used to determine whether or not the test compound has bound to the albumin. Using this method and others employing radiolabelled compounds, nine photoallergens have been shown to bind to protein under the influence of UV light. In contrast, a cinnamate sunscreen, which absorbs UV light but is not a photoallergen, does not bind under these conditions. The method is proposed as an in vitro screening procedure for potential photoallergens.