[An analysis of the serological characteristics of anti-mitochondrial M2 subtype in patients with drug-induced liver injury and primary biliary cholangitis].

Objective To analyze the serological characteristics of anti-mitochondrial antibody M2 subtype (AMA-M2) in patients with drug-induced liver injury (DILI) and primary biliary cholangitis (PBC), in order to provide reference for clinical differential diagnosis. Methods Laboratory data of 2802 DILI cases who visited the hospital between January 2011 and December 2017 were retrospectively collected. AMA-M2 positive patients were analyzed with respect to laboratorical findings, and serum data of 120 patients with primary biliary cholangitis (PBC) at the same period was taken as a control. A chi-square test was used for group comparisons. One-way ANOVA and rank sum tests was used for ALT, AST, ALP, GGT and three groups of immunoglobulin M. Results Among 2802 DILI patients, AMA-M2 positive rate was 5.1% (144/2 802), 77.1% (111/144) was DILI alone, 22.2% (32/144) was DILI with PBC, and 0.7% (1/144) was DILI with Sjogren's syndrome. An AMA-M2 level in DILI alone group was mostly mild and moderate than the PBC group and the DILI combined with the PBC group. There was significant difference between the two groups (P 0.05). ALT and AST levels of DILI alone group and DILI combined with PBC were (585.92 ± 653.04) U/L, (501.45 ± 512.67) U/L and (373.47 ± 502.60) U/L, (335.97 ± 513.96) U/L, respectively, which were significantly higher than PBC group [(106.33 + 134.08) U/L, (112.59 + 152.20) U/L]. There were statistically significant differences between the two groups (P < 0.05).The ALP level of DILI alone group was (152.58 + 81.46) U/L, which was lower than PBC group (237.86 + 215.09). The difference was statistically significant (P < 0.05). The level of immunoglobulin M in the DILI alone group was (1.76 ± 1.16) g/L, which was lower than PBC group (4.74 ± 5.74) g/L and the DILI combined with the PBC group (3.31 ± 1.68) g/L. There was significant difference between the two groups. During follow-up, 2.7% of patients with DILI had cirrhosis, 42.3% had lower AMA-M2 titer, 14.4% had lower AMA-M2 titer, 13.5% had higher AMA-M2 titer and five cases developed PBC. Conclusion AMA-M2 is not only positive in patients with PBC, but also low-to-medium or even high-level AMA-M2 may be detected in DILI patients. For AMA-M2-positive DILI patients, it is necessary to identify whether they are associated with PBC. Secondly, the levels of ALT, AST and ALP should be analyzed, and the patients should be on regular follow up for early and timely detection of drug-induced PBC. Key words: Primary biliary cholangitis; Drug-induced liver injury; Anti-mitochondrial M2 subtypes