HLA-DR3 antigens in erosive oral lichen planus, cutaneous lichen planus, and lichenoid reactions.

HLA antigens were examined in patients with erosive oral lichen planus (OLPe), cutaneous lichen planus (CLP), or lichenoid reactions (LR) adjacent to amalgam fillings. The control group had amalgam restorations in contact with the oral mucosa but without any reactions. A strong association was found between HLA-DR3 and OLPe, with an RR value of 21.0 (p less than 0.05). The corresponding values for CLP and LR were 2.3 and 1.5, respectively (NS). The haplotype A1-B8-DR3 was more frequently found in OLPe (p less than 0.05) and CLP (p less than 0.05) than in LR and controls (NS). The data indicate that OLPe, CLP, and LR, which present with virtually the same histopathologic features, are different in their association with HLA-DR3. Moreover, the increased frequency of HLA-DR3 in OLPe suggests an autoimmune component in the pathogenesis of this disorder.