Clinical significance of anti-neutrophil cytoplasmic antibodies (ANCA) in autoimmune liver diseases

Background/Aims: The clinical relevance of anti-neutrophil cytoplasmic anti bodies (ANCA) in autoimmune liver disease is unclear. Defining the antigeni c specificities of ANCA in these diseases may improve their clinical signif icance. Methods: We studied the target antigens of ANCA in 88 patients with autoimm une hepatitis, 53 patients with primary biliary cirrhosis, and 55 patients with primary sclerosing cholangitis by indirect immunofluorescence, antigen -specific enzyme-linked immunosorbent assays, and immunodetection on Wester n blot, using an extract of whole neutrophils as a substrate. We related th e data to clinical symptoms of autoimmune liver disease. Results: By indirect immunofluorescence, ANCA were present in 74% of patien ts with autoimmune hepatitis, 26% of patients with primary biliary cirrhosi s, and 60% of patients with primary sclerosing cholangitis, Major antigens were catalase, alpha-enolase, and lactoferrin, The presence of ANCA as dete cted by indirect immunofluorescence was associated with the occurrence of r elapses in autoimmune hepatitis, with decreased liver synthesis function in primary biliary cirrhosis and in primary sclerosing cholangitis, and with increased cholestasis in primary sclerosing cholangitis, ANCA of defined sp ecificities had only limited clinical relevance. Conclusions: ANCA as detected by indirect immunofluorescence seem associate d with a more severe course of autoimmune liver disease. The target antigen s for ANCA in these diseases include catalase, alpha-enolase, and lactoferr in, Assessment of the antigenic specificities of ANCA in autoimmune liver d isease does not significantly contribute to their clinical significance.