Wir überwinden Grenzen

A cell-based test allows the detection of soluble immune complexes in the smallest traces for the first time / Relevant for the research and diagnosis of autoimmune diseases and viral infections such as COVID-19

The human immune system produces antibodies during infections and inflammations. If these bind to their target, for example the pathogen, this is referred to as an immune complex. These complexes are considered to be an important driving force behind the intensification of rheumatoid arthritis, other autoimmune diseases and viral infections. Researchers at the Faculty of Medicine - University of Freiburg have now developed a test system using living cells that is around 1,000 times more sensitive than previous tests. In addition, the cell-based test indicates how large the immune complexes are and how strongly they affect the immune system. The study on the test development was published on November 29, 2021 in the journal EMBO: Molecular Medicine.

"Thanks to its high sensitivity, physicians could use the test to detect the onset of autoimmunity attacks very precisely in the future," says Dr. Philipp Kolb, research group leader at the Institute for Virology at the Medical Center - University of Freiburg. Even the smallest traces of immune complexes can be detected with the biological test system.

As a rule, the immune complexes remain locally concentrated and are quickly eliminated by special cells of the immune system once the disease or inflammation has been overcome. Autoantibodies, which recognize the body's own molecules as antigens, frequently occur in autoimmune diseases. As a result, large quantities of soluble, circulating immune complexes are found/form in the blood or body fluids. These are considered important drivers of immunopathology in certain autoimmune diseases such as systemic lupus erythematosus (SLE or lupus) or rheumatoid arthritis (RA). These immune complexes are recognized by immune cells, which leads to their activation and subsequent tissue inflammation.

"In addition to the highly sensitive detection of immune complexes, the new test system also allows their size to be measured. In our study, this factor demonstrably influenced the immune reactivity of immune complexes and thus provides important information on their immunological influence," said Prof. Dr. Hartmut Hengel, Medical Director of the Institute for Virology at the Medical Center - University of Freiburg. The study showed that the reactivity of soluble immune complexes in the blood of lupus patients increases with the severity of the disease.

Diagnostics already in use

The test system has already been used in initial studies. Researchers in Heidelberg successfully used it in a clinical study to investigate the role of immune complexes in the knee joint fluid of patients with rheumatoid arthritis.

In another clinical study, which is currently still in the review process, the Freiburg researchers used the test system to examine immune complexes in COVID-19 patients and to investigate a link between immune complexes and the severity of the disease.

In further steps, the test system is now to be certified and accredited. This would make it available for the diagnosis of inflammatory diseases outside of clinical studies.

Original title of the study: Detection and functional resolution of soluble immune complexes by an FcγR reporter cell panel

DOI: 10.15252/emmm.202114182

Link to the study: https://pubmed.ncbi.nlm.nih.gov/34842342/

Contact:
Dr. Philipp Kolb
Group leader
Institute for Virology
Medical Center - University of Freiburg
Phone: 0761 203-6611
philipp.kolb@uniklinik-freiburg.de

Prof. Dr. Hartmut Hengel
Medical Director
Institute for Virology
Medical Center - University of Freiburg
Phone: 0761 203-6533
hartmut.hengel@uniklinik-freiburg.de