Leukocyte adhesion molecules in oral lichen planus: a T cell-mediated immunopathologic process.

Oral lichen planus exhibits features of a mucosal type IV immunopathologic process. Adhesion molecules involved in the trafficking and homing of T lymphocytes to the subepithelial compartment were assessed by immunohistochemical methods. Laminin, type IV collagen and type VII collagen extracellular matrix components at the epithelial-connective tissue junction are significantly increased and serve as ligands for beta 1 integrins on lymphocyte membranes. Endothelial-associated intercellular adhesion molecule 1 and extracellular matrix basement membrane components are also significantly increased in the submucosa. Keratinocyte expression of major histocompatibility complex class II molecules and intercellular adhesion molecule 1 may serve as ligands for lymphocyte T cell receptor complex and beta 2 integrins, respectively. These adhesion molecules are probably involved in the trafficking of lymphocytes to the epithelial connective tissue interface in response to as of yet undefined antigens.