Induction and upregulation of adhesion receptors in oral and dermal lichen planus.

The expression pattern of well-defined cell surface adhesion receptors called VLA-family, LFA-1 and ICAM-1 was determined semiquantitatively in biopsies of oral (n = 12) and dermal lichen planus (n = 5) and compared to normal uninvolved human oral mucosa (n= 12) and skin (n= 12) using an indirect immunoperoxidase technique. In both oral and dermal lichen planus, an induction of the β1-integrins VLA-1 and VLA-3 and an upregulation of VLA-6 was found on T cells infiltrating the basement membrane zone. These cell surface molecules function as receptors for collagen, fibronectin and laminin. A focal induction of ICAM-1 on basal keratinocytes could be detected at sites of intramucosal T cells. These results suggest that investigated adhesion receptors are crucially involved in the aggregation of T cells in both conditions. Further investigations have to be done to determine the functional role of these adhesion receptors in lichen planus.