PBC Screen An IgG/IgA dual isotype ELISA detecting multiple mitochondrial and nuclear autoantibodies specific for primary biliary cirrhosis

A dual isotype (IgG IgA) enzyme-linked immunosorbent assay (ELISA) designed to provide enhanced detection of primary biliary cirrhosis (PBC)-specific autoantibodies against both major mitochondrial and nuclear antigens has been developed and recently become commercially available The assay (PBC Screen) simultaneously detects IgG and IgA autoantibodies to the immunodominant portions of the 3 major mitochondrial (MIT3) and nuclear (gp210 and sp100) antigens The aim of this study was to compare the performance of the PBC Screen to the combined performance obtained with individual IgG ELISAs to MIT3 gp210 and sp100 on a large group of selected patients from multiple centers A total of 1175 patients with PBC and 1232 subjects without PBC were evaluated Non-PBC groups included healthy controls (624) as well as individuals with autoimmune hepatitis (281) primary sclerosing cholangitis (77) viral hepatitis (91 hepatitis B and 98 hepatitis C) other liver diseases (31) and other infectious or autoimmune diseases (30) The PBC Screen at the receiver operator characteristic optimized cutoff of 278 units had an overall sensitivity of 83 8% specificity of 94 7% and area under curve of 0 9212 This was similar to the specificity of 96 1% obtained by the combined results of individual MIT3 sp100 and gp210 IgG ELISAs (kappa index at 0 898) Of the 253 PBC patients without AMA detectable by immunofluorescence 113 (44 7%) were interpreted as positive for PBC-specific autoantibodies In conclusion the PBC