SARS-CoV-2, the virus that causes COVID-19, infects immature red blood cells, reducing oxygen in the blood and hindering immune response, according to a new study published in Stem Cell Reports.
Researchers at Canada-based University of Alberta examined the blood of 128 COVID-19 patients, including critically ill individuals admitted to intensive care, those who were hospitalized with moderate symptoms, and those who had milder symptoms who only spent a few hours in the hospital.
Four key findings:
1. The researchers found that, as the disease became more severe, more immature red blood cells flooded blood circulation, sometimes accounting for up to 60 percent of total cells in the blood. By comparison, immature red blood cells account for less than 1 percent, or none at all, in a healthy individual's blood. The problem is that immature red blood cells do not transport oxygen.
2. "Immature red blood cells reside in the bone marrow and we do not normally see them in blood circulation," Shokrollah Elahi, MD, PhD, study lead and associate professor at the university, told Troy Media. "This indicates that the virus is impacting the source of these cells. As a result, and to compensate for the depletion of healthy immature red blood cells, the body is producing significantly more of them in order to provide enough oxygen for the body."
3. Immature red blood cells are highly susceptible to COVID-19 infection. As immature red blood cells are destroyed by the virus, the body is unable to replace mature red blood cells, and the ability to transport oxygen in the bloodstream is impaired. "We have demonstrated that more immature red blood cells mean a weaker immune response against the virus," Dr. Elahi said.
4. Dr. Elahi's team also tested various drugs to see whether they could reduce immature red blood cells' susceptibility to the virus. "We tried the anti-inflammatory drug dexamethasone, which we knew helped to reduce mortality and the duration of the disease in COVID-19 patients, and we found a significant reduction in the infection of immature red blood cells," Dr. Elahi said. "So we are not repurposing or introducing a new medication; we are providing a mechanism that explains why patients benefit from the drug."