Performance of indirect immunofluorescence test and immunoblot tests in the evaluation of antinuclear and antimitochondrial antibodies

BACKGROUND: Antinuclear antibodies (ANA) and antimitochondrial antibodies (AMA) have essential markers for the diagnosis of autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC). These autoantibodies are detecting different laboratory methods. In this study, we studied the diagnostic performance of used methods in detecting ANA and AMA. METHODS: The autoantibody profiles of patients with AIH and PBC groups were analyzed with the indirect immunofluorescence test (IIF) and liver-specific antigens containing immunoblot test (IB). RESULTS: There were 45 (87%) women in the study group and 8 (53%) women in the control group. The mean age of the patients was 50.5 ± 14.21 years old. The serum ALT and AST levels were higher in AIH, and ALP, GGT, and Ig M were higher in PBC. IIF test results among AIH/PBC groups; there was no difference in overall ANA positivity (p: 0.078). AMA was negative in all patients with AIH but positive in 83.3% of patients with PBC. IB test results among AIH/PBC groups; antibodies against PDGH, LKM-1, and Scl-70 were not observed in any patient with AIH/PBC. Except for M2 (p: 0.001) and M23E (p: 0.007) antibodies, there was no significant difference in antibodies between groups. Out of five PBC patients with negative AMA by IIF method, one was positive for AMA-M2, two were positive anti-gp210, and three were positive anti-M2-3E, but anti-sp100 was negative in all of them by the IB. DISCUSSION: AIH/PBC has complex associations with different autoantibodies, and some of these antibodies are not readily detected by the IIF test. IB assays with a wide variety of liver-specific antigens may be helpful in the diagnosis (especially in patients with AMA negative PBC) and follow-up in AIH/PBC patients.