INTRAEPITHELIAL SUBPOPULATIONS OF T-LYMPHOCYTES AND LANGERHANS CELLS IN ORAL LICHEN-PLANUS

This study has addressed the question of whether there is selective re cruitment and distribution of intra-epithelial leucocytes in lesions o f oral lichen planus (OLP), T-Iymphocyte subsets were examined in the epithelium and peripheral blood of patients and controls using flow cy tometry and double immunofluorescence, and the relationship between ke ratinocyte intercellular adhesion molecule-1 (ICAM-1) expression with T-lymphocyte and Langerhans cell (LC) distribution was examined, The c irculating 'memory' subset (CD45RO(+)) of T-helper cells (CD4(+)) was increased from 49.1% in controls to 65.7% in patients (P = 0.005), whi le the 'naive' subset (CD45RA(+)), which was absent from control epith elium, comprised 24% of helper cells in OLP (P=0.016), Fewer LC expres sed CD45RO in OLP than in controls (P=0.037) and all T-cell and LC cou nts were significantly raised in ICAM-1-expressing areas of epithelium . These data demonstrate changes in intra-epithelial T-lymphocyte and LC populations compared with normal oral mucosa and suggest there is s elective recruitment in OLP. In addition, keratinocyte ICAM-1 expressi on does appear to be associated with accumulation of infiltrating T ly mphocytes and LC.