Investigation of liver-specific autoantibodies by immunoblot method in patients with suspected autoimmune liver disease and positive autoantibody findings

Aim: To investigate liver specific autoantibodies by immunoblot in adults suspected of autoimmune liver disease (AILD) who were positive for autoantibodies by indirect immunofluorescence (IIF), and to assess concordance between IIF patterns and antigen specific results. Materials and Methods: Sera from 96 adults with suspected AILD were examined retrospectively. Samples with ANA/AMA/ASMA/LKM screening by IIF that patterns were recorded under the ICAP classification were analyzed by immunoblot if the pattern suggested AILD. Semiquantitative results were compared with clinical data. Results: The mean age was 59.9±12.8 years; 93.8% were female. Liver function tests were elevated in 81.2%. AMA was the most common IIF pattern; nuclear membrane, multiple nuclear dots and anti centromere patterns were less frequent; 54.2% of cases showed multiple patterns. Immunoblot detected at least one autoantibody in 89.6%. Anti M2 and anti M2 3E were most frequent patterns. They were also often co positive. Nuclear antibodies (anti-Ro52, anti-Sp100, anti-Gp210, anti-PML) and other antibodies appeared at varying rates. In 23% of AMA negative cases, anti-M2 or anti-M2 3E were positive. Anti-F actin, anti-LKM 1,anti- SLA/LP and anti-LC 1 positivity occurred in autoimmune hepatitis (AIH) and overlap syndromes. Conclusion: IIF is useful for autoantibody screening, but antigen-specific immunoblot improves diagnostic sensitivity, particularly in patients with mixed-pattern or AMA-negative. Combined interpretation of IIF, immunoblot, and clinical data is essential for accurate diagnosis and follow-up. Keywords: indirect immunofluorescence; immunoblot; primary biliary cholangitis; autoimmune hepatitis.