Antimitochondrial antibody measurements in the diagnosis of antimitochondrial antibody-negative and alkaline phosphatase-positive primary biliary cholangitis
image: False-negative AMA-negative PBC can be due to insensitive AMA tests, delayed seroconversion, or medication-induced suppression of AMA. These should be considered and excluded, and true AMA-negative PBC should be confirmed by ANA (anti-gp210 and anti-sp100). The presentation, progression, and response to treatment of AMA-negative PBC have been shown to be similar to those of AMA-positive PBC. Liver biopsy is not necessary to make a diagnosis of AMA-negative PBC except in the few cases where ANA (anti-gp210 and anti-sp100) are also negative. GLOBE and UK-PBC scores remain useful clinical tools for prognostication and can be applied to AMA-negative cases, as such cases were included in validation studies of these tools. Although AMA-negative PBC is often discussed as an “atypical” entity separate from AMA-positive PBC, the fact that progression and outcomes are virtually identical indicates that the presence or absence of AMA appears not to significantly influence disease development or progression. Therefore, labeling AMA-negative PBC as “atypical” is somewhat misleading. The findings indicate that future research on PBC should focus on improving un-derstanding of its pathogenesis and on the discovery of new targeted therapies, including for AMA-negative cases.
Credit: Karol Suchowiecki, George Y. Wu
PBC is a chronic autoimmune liver disease injuring small/medium intrahepatic bile ducts, often progressing to cirrhosis. AMA negativity is not one entity but includes laboratory issues, delayed seroconversion, UDCA‑related seroreversion, and true AMA‑negative PBC.
AMA Measurement
Five assays exist: IIF (lowest sensitivity; only 15% react to MIT3), immunoblot, ELISA, Luminex bead, and enzyme inhibition. ELISA and immunoblot detect M2 antigens and are superior to IIF; 10–73% of IIF‑negative cases become positive on retesting.
Contributors to AMA Negativity
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Laboratory: Low assay sensitivity causes false negatives.
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Natural history: 10–26% seroconvert over up to 3 years.
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Pharmacological: UDCA can decrease AMA titres (seroreversion).
True AMA‑Negative PBC
Epidemiology: 5–10% of PBC; higher (17–30%) in some non‑white cohorts. Women affected 10× more than men.
Pathogenesis: T‑cells damage biliary epithelial cells; B‑cells produce AMAs, which do not cause damage. Proinflammatory cytokines reduce AE2 function, acidifying bile and damaging bile ducts and hepatocytes. In AMA‑negative PBC, B‑cell response is absent but damage is indistinguishable, explaining identical outcomes.
Presentation: Similar to AMA‑positive PBC—cholestasis, fatigue, pruritus. Progression and outcomes are comparable.
Diagnosis
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If AMA negative by IIF, retest by ELISA or similar assay.
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If negative, test for ANA (anti‑gp210, anti‑sp100).
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Any positive confirms PBC.
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If all negative, liver biopsy is required (nonsuppurative bile duct damage, ductopenia, possible granulomas/fibrosis).
Exclude other cholestatic causes (obstruction, lesions, drug‑induced, PSC, IgG4) using CT, MRCP, serology, and if needed ERCP.
Differential Diagnosis
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PSC: MRCP and biopsy definitive; ANCA lacks specificity.
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Autoimmune hepatitis: Hepatocellular pattern, elevated IgG, autoantibodies.
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Drug‑induced cholestasis: Temporal relationship to drug.
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Lesions/obstruction: Evaluated by ultrasound, CT/MRI, ERCP/EUS.
Treatment
UDCA 13–15 mg/kg/day is first‑line. Outcomes in AMA‑negative cases are similar to AMA‑positive PBC. Obeticholic acid for UDCA non‑responders; bezafibrate as alternative. Elafibranor and seladelpar approved for inadequate UDCA response; no data in AMA‑negative PBC. GLOBE and UK‑PBC scores predict outcomes in both groups.
Discussion
Incidence of biopsy‑proven AMA‑negative PBC is 9.7–20%, similar in symptomatic and asymptomatic patients. Most remain AMA‑negative; 10–26% seroconvert over 3 years. Delayed seroconversion is not clinically relevant because ANA serology or biopsy diagnoses most cases.
AASLD/EASL guidelines state repeated AMA testing is not indicated once negative, but repeat testing with a sensitive assay (e.g., ELISA) may identify false‑negative IIF results. ANA testing is recommended to confirm AMA‑negative PBC, usually avoiding biopsy. If initial testing used a low‑sensitivity assay or ANA is unavailable, repeat AMA testing is advised.
Historically, lack of AMA delayed diagnosis; recent studies show earlier detection with ANA and no difference in outcomes versus AMA‑positive PBC. Labelling AMA‑negative PBC as "atypical" is misleading, as progression is virtually identical.
Limitations include small, retrospective studies. Future trials should include longitudinal AMA/ANA changes, new biomarkers, and targeted therapies.
Conclusions
False‑negative AMA‑negative PBC can result from insensitive tests, delayed seroconversion, or medication effects; true AMA‑negative PBC should be confirmed by ANA (anti‑gp210, anti‑sp100). Presentation, progression, and treatment response are similar to AMA‑positive PBC. Liver biopsy is unnecessary unless ANA is also negative. GLOBE and UK‑PBC scores remain useful. AMA status does not significantly influence progression. Future research should focus on pathogenesis and new targeted therapies.
Full text
https://www.xiahepublishing.com/2310-8819/JCTH-2026-00117
The study was recently published in the Journal of Clinical and Translational Hepatology.
The Journal of Clinical and Translational Hepatology (JCTH) is owned by the Second Affiliated Hospital of Chongqing Medical University and published by XIA & HE Publishing Inc. JCTH publishes high quality, peer reviewed studies in the translational and clinical human health sciences of liver diseases. JCTH has established high standards for publication of original research, which are characterized by a study’s novelty, quality, and ethical conduct in the scientific process as well as in the communication of the research findings. Each issue includes articles by leading authorities on topics in hepatology that are germane to the most current challenges in the field. Special features include reports on the latest advances in drug development and technology that are relevant to liver diseases. Regular features of JCTH also include editorials, correspondences and invited commentaries on rapidly progressing areas in hepatology. All articles published by JCTH, both solicited and unsolicited, must pass our rigorous peer review process.
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