Antigenicity of Dna Induced by Photoaddition of 8‐methoxypsoralen

Rabbits immunized with sonicated DNA UV‐irradiated (365 nm) in the presence of 8‐methoxypsoralen (8‐MOP) produced a specific antiserum directed against DNA‐8‐MOP‐photoadduct. None of the long chain DNA preparations modified photochemically in the same way elicited an immunological response, although all of them gave a positive immunodiffusion test on agarose with the antiserum directed against DNA‐8‐MOP‐photoadduct. A positive reaction has also been demonstrated in the indirect immunofluorescence test, using as a source of cellular native DNA Crithidia luciliae cells treated with 8‐MOP and irradiated at 365 nm (UVA). A possible use of the specific antiserum for detecting the formation of DNA‐8‐MOP‐photoadduct, in the skin and/or lymphocytes of patients with psoriasis treated by combination of 8‐MOP and UVA irradiation, is suggested.