SARS-CoV-2 can cause a significant inflammatory response in the immune cells infected with the virus, thus contributing to severe COVID-19, two papers recently published in Nature suggest.
The research also points to the protection provided by mRNA COVID-19 vaccines.
The studies suggest that inflammation is triggered when two types of white blood cells, macrophages in the lungs, and monocytes in the blood, are infected with the virus.
“Judy Lieberman, an immunologist at the Boston Children’s Hospital in Massachusetts, and her colleagues looked at blood samples from people with COVID-19. They found that about 6% of monocytes—‘early responder’ immune cells that patrol the body for foreign invaders—were undergoing a type of cell death associated with inflammation, known as pyroptosis,” Nature says. “The researchers also looked at another type of immune cell, macrophages, in the lungs of people who had died of COVID-19. … The team found that about a quarter of macrophages had activated inflammasomes, and a fraction of those had indeed been infected with the virus.”
“The studies also provide conclusive evidence that the virus can infect and replicate in immune cells — and reveal how it enters those cells,” according to Nature. “But Lieberman says that not all antibodies facilitate viral entry. The team found that antibodies produced by people who received the mRNA vaccine developed by Pfizer and BioNTech did not allow monocytes to take up the virus.”