Immunohistochemical and serological comparison of idiopathic and hepatitis C virus-associated forms of oral lichen planus.

The oral form of the inflammatory disease lichen planus occurs spontaneously due to unknown aetiological factors. However, it has recently been observed to occur with increased frequency in patients infected with the hepatitis C virus. Because of the prominent role of adhesion molecules in immune cell interactions, we have compared the expression of these antigens in the hepatitis C virus-associated and idiopathic forms of the disease. The results show similar patterns of expression of very late activation antigen-4, lymphocyte function-associated antigen-3 and intercellular adhesion molecule-1, but relatively elevated levels of these antigens in oral lichen planus patients with no hepatitis C virus infection. In addition to differences in Langerhans cell distribution, serum levels of "soluble" intercellular adhesion molecule-1 as well as immunoglobulin G were significantly increased in the hepatitis C virus-associated group. These findings show that there are some differences in the lesional and systemic immune reactivities of the two types of oral lichen planus which may be related to possibly distinct pathogenic mechanisms.