Oral mucosal keratinocytes express RANTES and ICAM-1, but not interleukin-8, in oral lichen planus and oral lichenoid reactions induced by amalgam fillings

Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa characterized by a band-like accumulation of lymphocytes in the connective tissue adjacent to the basement membrane as well as intraepithelially. Amalgam fillings can induce oral lichenoid reactions (OLR) that are similar to OLP. The adhesion molecule ICAM-1 and the chemokines interleukin-8 and RANTES all play central roles in leucocyte trafficking. The aim of this study was to investigate the possible role of these molecules in the migration of leucocytes into the oral mucosa in OLP and OLR. Standard immunoperoxidase techniques were used to visualize the expression of ICAM-1, RANTES and interleukin-8 in frozen biopsy sections. ICAM-1 was expressed by endothelial cells, but not by keratinocytes, in normal oral mucosa. ICAM-1 was expressed by keratinocytes in 11 of 12 biopsies of OLP and in six of seven biopsies of OLR. In all of these cases ICAM-1 was also expressed by endothelial cells and leucocytes. Although not present in normal oral mucosa, RANTES was expressed by keratinocytes in 21 of 24 biopsies of OLP and in seven of seven cases of OLR. Interleukin-8 was not detected in any of the samples. The expression of ICAM-1 and RANTES by epithelial keratinocytes in the oral mucosa in OLP and OLR could be a key inflammatory mechanism in these diseases.