Serum from lichen planus patients reacts with fetal skin tissues.

Lichen planus specific antigen (LPSA) is a lesion-specific marker that differentiates lichen planus from other dermatoses. Serum from lichen planus patients reacted in the indirect immunofluorescent test with fetal epidermis. The reaction was not observed between serum from people with no clinical history of lichen planus and fetal skin tissues. Adsorption of lichen planus serum with a fetal skin extract removed the antibody to LPSA. Adsorption with equivalent amounts of adult normal skin did not remove the serologic activity of LP serum to fetal skin. ELISA test serum from lichen planus patients bound to fetal skin antigen extract to a greater extent than did serum from normal individuals or from patients with non-lichen planus dermatoses, although the quantity of antibody bound in these three groups was not significantly different.