Serious Covid-19 diseases can follow very different paths. However, there appear to be some commonalities in the immune response. According to a new study, the recovery process can be seen primarily from a certain blood count.
COVID-19 can affect many organs and follow very different paths. However, the course of the disease largely depends on the immune response. Since this reaction is reflected in the blood, a team from the German Center for Neurodegenerative Diseases (DZNE) looked for similarities. To do this, DZNE scientists repeatedly examined the blood of 139 Covid-19 patients who had to be treated in intensive care. Patients were between 21 and 86 years old, most were male. 105 recovered sufficiently to be discharged from the ICU and 34 patients died.
The neutrophil count decreases during recovery
Analyzes revealed that recovery from severe COVID-19 is characterized by the gradual decline of certain white blood cells: neutrophils. They are the most common white blood cells and act as one of the first lines of defense against pathogens in the immune system’s arsenal. “We found that patients with severe COVID-19 have a high number of mature, that is, fully developed, neutrophils in their blood, the amount of which decreases during the healing process,” says lead author Dr. Amit Frischberg.
Levels of other white blood cells have also changed over time, with some going down while others going up. “However, these changes are less pronounced than in neutrophils,” says Frishberg.
Increase associated with poor prognosis
But the researchers could also observe the opposite case: an increase in mature neutrophils over a longer period of time leads to a high probability of death in ICU patients. “This may be because the steady increase is accompanied by an excessive and therefore harmful immune response,” says Frishberg.
The researchers also discovered other changes during recovery that affect the molecular signaling pathways and regulatory mechanisms of the immune system. “What is extraordinary about our results is that the recovery in all patients followed the same biological pattern, despite individual differences in the time course of the disease. So there is a common thread, so to speak. We found no evidence in our data that the healing process after severe COVID-19 disease can follow different paths, ”Frishberg points out.
Biomarkers for prognosis
Based on the findings, the authors now propose to use the number of neutrophils in the blood as a biomarker for severe Covid-19 prognosis.
For their analysis, the scientists relied mainly on blood transcriptomes. These datasets reflect the gene activity of all blood cells at any given time. As a rule, more than 10,000 different genes are registered. Blood transcriptomes provide a very detailed picture of the immunological process. This very complex data was analyzed using computer-aided methods.