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

Background/Aims: The clinical relevance of anti-neutrophil cytoplasmic antibodies (ANCA) in autoimmune liver disease is unclear. Defining the antigenic specificities of ANCA in these diseases may improve their clinical significance. Methods: We studied the target antigens of ANCA in 88 patients with autoimmune 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 Western blot, using an extract of whole neutrophils as a substrate. We related the data to clinical symptoms of autoimmune liver disease. Results: By indirect immunofluorescence, ANCA were present in 74% of patients with autoimmune hepatitis, 26% of patients with primary biliary cirrhosis, and 60% of patients with primary sclerosing cholangitis, Major antigens were catalase, alpha-enolase, and lactoferrin, The presence of ANCA as detected by indirect immunofluorescence was associated with the occurrence of relapses 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 specificities had only limited clinical relevance. Conclusions: ANCA as detected by indirect immunofluorescence seem associated with a more severe course of autoimmune liver disease. The target antigens for ANCA in these diseases include catalase, alpha-enolase, and lactoferrin, Assessment of the antigenic specificities of ANCA in autoimmune liver disease does not significantly contribute to their clinical significance.