Increased frequency of HLA-DR6 allele in Italian patients with hepatitis C virus-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 HCV infection has been found in LP patients in England and northern France, and significant differences in serum HCV RNA levels or HCV genotypes have not 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 of symptoms outside the liver. Objectives To assess whether major histocompatibility complex class II alleles play a part in the development of HCV-related LP. Methods Intermediate-resolution DRB typing by hybridization with oligonucleotide 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 clinically comparable disease control group of 60 Italian OLP patients without HCV infection (anti-HCV and HCV RNA negative), and in 145 healthy unrelated Italian bone marrow donors without evidence of liver disease or history of 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 infection (52% vs. 18%, respectively; P-c (P-corrected) = 0.028, relative risk = 4.93). We did not find any relationship between mucocutaneous LP, HCV infection and HLA-DR alleles, Conclusions HCV-related OLP therefore appears to be a distinctive subset particularly associated with the HLA class II allele HLA-DRG, This could partially explain the peculiar geographical heterogeneity of the association between HCV and LP.