Hepatitis C viral (HCV) infection has been shown to lead to autoimmune phenomena. Antineutrophil cytoplasmic antibodies (ANCA) have been known to be present in several autoimmune liver diseases. This study aimed to evaluate the prevalence of ANCA in sera of patients with antinuclear antibody (ANA)-positive chronic hepatitis C (CH-C) and to characterize ANCA antigens by Western blot compared with HCV-negative autoimmune hepatitis (AIH).
Methods: Ninety sera obtained from 20 patients with ANA-positive CH-C, 20 patients with ANA-negative CH-C, 20 patients with AIH, 6 patients with primary screlosing cholangitis (PSC) and 24 healthy controls were tested using an indirect immunofluorescence assay, cell ELISA and Western blotting to detect ANCA.
Results: In the indirect immunofluorescence assay, ANCA was found in 60% (12/20) of patients with ANA-positive CH-C, 100% (20/20) of patients with AIH and 33.3% (2/6) of patients with PSC, but in none of patients with ANA-negative CH-C (n = 20) or healthy controls (n = 24). The staining pattern observed in sera of these patients was a peculiar mixture of both cytoplasmic and perinuclear patterns. The mean ANCA titer by cell ELISA was significantly (p < 0.01) higher in patients with AIH compared with ANA-positive or ANA-negative CH-C patients or healthy controls. However, no correlation was found between ANCA titers and ANA titers, serum alanine amino transferase (ALT) or IgG levels in either ANA-positive CH-C or AIH. Western blots of ANCA-positive sera from ANA-positive CH-C patients revealed two bands corresponding to molecular weights of 72 and 46 kDa and there was no differencies in ANCA antigens compared with that from AIH patients.
Conclusions: We found an increased incidence of ANCA in ANA-positive CH-C patients. ANCA in ANA-positive CH-C patients is thought to be one of autoimmune phenomena lead by HCV infection because no difference was observed in the epitope of ANCA antigens between patients with CH-C and AIH.