Researchers from the US and China have found that COVID-19 can destroy T cells, a type of lymphocyte that plays a key role in the body’s immune system in a similar way to HIV.
T lymphocytes, also known as T cells, are key for identifying and eliminating pathogens in the body. They work by finding a cell infected by a pathogen, in this case the virus behind COVID-19, poking a hole in its membrane, and injecting it with toxic chemicals. These toxic chemicals then kill both the virus and the cell.
Now, a team of researchers from Shanghai and New York found that a unique structure in the virus’ spike protein fuses the virus and T cell together when they come into contact. This allows the virus to enter the T cell and essentially take over its behavior, switching off its normal pathogen-fighting functions.
This finding comes after a clinical report released by the Chinese People’s Liberation Army’s Institute of Immunology in February stating that T cell number could significantly drop in patients with COVID-19. This was especially the case for those who were elderly or requiring intensive care treatment. They then correlated lower counts of T cells with a higher mortality risk.
Confirmed by autopsy examination of over 20 patients, Chinese doctors compared the damage to their internal organs to a combination of SARS and AIDS.
Despite this, the authors of the study said that although HIV is able to replicate inside of T cells, essentially turning them into ‘HIV factories’, there is currently no evidence that the coronavirus can do the same. This means that although the virus is able to infect T cells, it may also end up dying together with them, without replicating beforehand.
How this mechanism works however is still under debate. This comes especially as some patients remain symptom-free for weeks, despite this T cell interaction. More information is also needed to understand why some critically ill patients experience cytokine storms, where their immune systems go on overdrive and kill healthy cells, relative to this new finding.
The authors of the research said that further investigation into how the coronavirus infects primary T cells will nevertheless lead to ‘new ideas about pathogenic mechanisms and therapeutic interventions’.