Increased frequency of HLA-DR6 allele in Italian patients with hepatitis Cvirus-associated oral lichen planus

Background Recent controlled studies have confirmed that hepatitis C virus (HCV) is the main correlate of liver disease in patients with lichen planus (LP), mainly in southern Europe and Japan, However, a low prevalence of HC V infection has been found in LP patients in England and northern France, a nd significant differences in serum HCV RNA levels or HCV genotypes have no t been found between LP patients and controls. Thus host rather than viral factors may be prevalent in the pathogenesis of HCV-related LP. The HLA-DR allele may influence both the outcome of HCV infection and the appearance o f symptoms outside the liver. Objectives To assess whether major histocompatibility complex class II alle les play a part in the development of HCV-related LP. Methods Intermediate-resolution DRB typing by hybridization with oligonucle otide probes was performed in 44 consecutive Italian oral LP (OLP) patients with HCV infection (anti-HCV and HCV RNA positive), in an age, sex and cli nically comparable disease control group of 60 Italian OLP patients without HCV infection (anti-HCV and HCV RNA negative), and in 145 healthy unrelate d Italian bone marrow donors without evidence of liver disease or history o f LP and with negative tests for HCV, Results Patients with exclusive OLP and HCV infection possessed the HLA-DRG allele more frequently than patients with exclusive OLP but without HCV in fection (52% vs. 18%, respectively; P-c (P-corrected) = 0.028, relative ris k = 4.93). We did not find any relationship between mucocutaneous LP, HCV i nfection and HLA-DR alleles, Conclusions HCV-related OLP therefore appears to be a distinctive subset pa rticularly associated with the HLA class II allele HLA-DRG, This could part ially explain the peculiar geographical heterogeneity of the association be tween HCV and LP.