According to a study published in the Journal of Clinical Investigation, patients with severe Covid-19 have significantly elevated levels of a specific type of immune cells in their blood called monocytic myeloid-derived suppressor cells otherwise known as M-MDSC. They evaluated the cell's potential role in COVID-19.
Anna Sorensen, a researcher from Karolinska Institute, said the results helped increase the understanding of what causes severe Covid-19. She detailed the connection between the early innate immune system (includes M-MDSC ) and later adaptive immune system, including T cells.
For protecting the body against viral infections like Covid-19, T-cells plays a significant role. Whereas, M-MDSCs have been shown to increase in other inflammatory conditions. The suppressive effect of M-MDSC on T cell activity has been established.
However, the role of M-MDSC in respiratory infections is unknown. It is crucial to understand the role of M-MDSCs in this disease since low levels of T-cells are a hallmark of Covid-19.
The study was conducted among 147 patients who showed mild to fatal symptoms of Covid-19. Repeated samples were collected from the respiratory tract and the blood of the selected patients. These results were then compared with patients with influenza and healthy individuals.
"There is also a strong clinical connection, as we could potentially use the results to find new biomarkers for severe illness," Sorensen added.
The final results reveal that patients with severe Covid-19 have significantly elevated levels of M-MDSCs in blood compared to milder cases and healthy individuals. Research also showed that Covid-19 patients showed signs of impaired function and had fewer T-cells in blood than healthy subjects.
The researchers proved that the levels of M-MDSCs early in the course of disease seemed to reflect subsequent disease severity.