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A weak immune response is not the cause of dangerous lung failure in severe Covid-19 infections. Rather, these infections appear to be caused by an overreaction of the immune system. This is the conclusion of a research team from the Ruhr-Universität Bochum (RUB) and the Duisburg-Essen university hospital led by Professor Nina Babel, director of the Center for Translational Medicine at the RUB Marien Hospital Herne clinic.
The team from the Marien Hospital and the Virology department of Ruhr-Universität Bochum (RUB), as well as the Infectious Diseases Clinic, the Anesthesiology Clinic and the Essen Institute of Virology of University Medicine studied specific antibodies and T cells occurring in recovered, seriously ill and deceased Covid-19 patients. The researchers identified comparable immune reactions in clinical follow-up. They report their findings in the journal Cell Report Medicine as of August 29, 2020.
How the immune system fights viruses
Antibodies and T lymphocytes are among the most important elements of the immune defense against viruses. Antibodies prevent viruses from entering the host cell by binding to certain virus receptors. They also mark infected cells for other immune system players, which can kill infected cells. Virus-specific T lymphocytes, on the other hand, can kill infected cells directly and very efficiently.
During the last weeks, some studies have been published on the analysis of these specific Sars-Cov-2 cell-destroying T cells in patients with Covid-19. Studies demonstrated the detection of such cells in recovered Covid-19 patients, suggesting their protective antiviral effect. On the other hand, some studies indicate that an excessive immune response could be the cause of severe Covid-19. The role of Sars-Cov-2 specific T cells in this exaggerated immune response is unclear.
Critically ill patients have the same or stronger immunity than recovered patients
In the current study, the research team looked at immune responses in Covid-19 patients as the disease progressed. “This is how we wanted to investigate the role of T cells and antibodies in controlling infection and disease,” explains Nina Babel, who led the study. “The novel aspect of our study is that we analyzed T cells and Sars-Cov-2 specific antibodies in relation to disease progression and viral clearance. We found that a strong T cell and non-antibody response could be detected. only in patients with mild Covid-19 patients who had recovered from virus infection. ” Similar or even stronger immunity to Sars-Cov-2 was found in patients who had been critically ill and suffering from Covid-19-related lung failure.
“The total number of specific immune cells, as well as their functionality, was no better in the patients who survived Covid-19 than in those who died from it,” says Dr. Ulrik Stervbo, head of laboratory at the Center for Translational Medicine. There was also no difference in the strength and functionality of the immune response between patients who still had and those who had cleared a Sars-Cov-2 infection.
Excessive immune response plays an important role
“Although more studies will be necessary to understand the specific mechanism of Covid-19 development, our data suggest that an excessive response of Sars-Cov-2 specific T cells may cause immunopathogenesis leading to Covid-19-related lung failure,” Nina Babel points out. “The results of current studies on the successful application of immunosuppressive therapies in Covid-19 support this hypothesis,” concludes Professor Timm Westhoff, Director of Medical Clinic I at Marien Hospital Herne.
Story Source:
Materials provided by Ruhr University Bochum. Original written by Meike Drießen; translated by Donata Zuber. Note: Content can be edited for style and length.
