Immunologic findings of oral lichen planus.

Immunofluorescence (IFL) examination in lichen planus (LP) often reveals fibrin deposition in the basement membrane (BM) zone and colloid bodies (CB) giving a positive IgM fluorescence. Oral biopsies were taken from the involved buccal mucosa of 10 LP patients. IFL examination showed fibrin deposition in the BM area of all patients but in none of the seven controls. CB were found in the upper connective tissue of 5/10 oral and 3/3 skin specimens and they were always positive for fibrin, IgM and keratin. Positive staining with keratin antiserum suggests the epithelial origin of CB but the importance of fibrin and IgM staining remains unknown. Double IFL staining revealed that in areas of heavy fibrin deposition and CB formation the laminin and fibronectin staining was absent, suggesting a damage to BM. Moreover, IFL examinations with serum amyloid P (SAP) antiserum and basic fuchsin (BF) showed alterations indicating that upper connective tissue elastic fiber system is also involved in oral LP.