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Improved accuracy for the diagnosis of autoimmune hepatitis
Autoimmune hepatitis (AIH) is a rare disease that affects around 23 in 100,000 people in Germany. The immune system attacks the patient's own liver for unknown reasons. If left untreated, the disease can lead to liver cirrhosis and make a liver transplant necessary. In most patients, the disease can be well controlled with immunosuppressive therapy, thus preventing the development of cirrhosis.
AIH can present in many different ways, and the diagnosis requires the exclusion of other (liver) diseases and the performance of blood tests and often a liver biopsy. The blood of patients with AIH often shows an increase in immunoglobulin G (IgG), a class of antibodies, i.e. proteins that neutralize viruses and bacteria, for example. Antinuclear and smooth muscle antibodies are also frequently found. These are special antibodies that are directed against the body's own structures, so-called autoantibodies.
The diagnostic problem is that these autoantibodies cannot be detected in all patients with AIH and are also found unspecifically in people with other admissions.
In the search for more accurate antibody tests to improve diagnostic accuracy, Dr. Taubert and Dr. Engel, first authors of the current paper, became aware of a special feature of IgG in patients with AIH.
IgG in patients with AIH bind to many different proteins and are polyreactive. Among other things, they also bind to the protein HIP1R, which is found throughout the body. The binding of polyreactive IgG (pIgG) was investigated in over 1,000 samples from ten European centers. It was shown that pIgG are more accurate for the diagnosis of AIH than conventional autoantibodies. The detection of pIgG also identifies AIH patients in whom no conventional autoantibodies are detectable.
The results have been published at a high level in Hepatology (Taubert, R., Engel, B., et al., (2021), Quantification of polyreactive immunoglobulin G facilitates the diagnosis of autoimmune hepatitis. Hepatology. Accepted Author Manuscript.
It is hoped that the determination of pIgG can spare some patients liver biopsies in the future. In contrast to conventional methods, the result can also be obtained within one day.
In future, the test should be made available to as many laboratories as possible. A patent has been granted by the European Patent Office.
Dr. Taubert and Dr. Engel will work with Dr. Jäckel to further develop and use the test in the Clinical Department and in other projects.