Cell: Reveals that T cells play a leading role in controlling SARS-CoV-2 and reducing the severity of COVID-19.

!--webeditor:page-title-- September 23, 2020 // --- Since SARS-CoV-2 first appeared, scientists have been trying to understand whether the immune system sometimes does more harm than good during the acute phase of COVID-19.
study, researchers from the La Hoya Institute of Immunology in the United States clearly supported the beneficial effects of the immune system.
results were published online September 16, 2020 in the journal Cell under the title "Antigen-specific adaptive immunity to SARS-CoV-2 in acute COVID-19 and associations with age and disease severity".
from Cell, 2020, doi:10.1016/j.cell.2020.09.038.
The study confirms that multi-layered virus-specific immune responses are important for controlling SARS-CoV-2 coronavirus infection during acute stages and reducing the severity of COVID-19 disease, with most evidence suggesting that T-cells are much more effective than antibodies.
, on the other hand, weak or un coordinated immune responses indicate adverse outcomes of the disease.
results suggest that candidate vaccines should focus on causing a wide range of immune responses, including antibodies, auxiliary T-cells, and killer T-cell responses, to ensure protective immunity.
, co-author of the paper and professor at the Center for Infectious Diseases and Vaccines at the La Hoya Institute of Immunology, said, "Our observations may also explain why older COVID-19 patients are more susceptible to the disease."
As we age, the T-cell pool that can be activated by a particular virus decreases and the body's immune response becomes less coordinated, which appears to be a factor that makes older people particularly vulnerable to severe or fatal COVID-19 effects. Dr. Alessandro Sette, co-author of the
paper and a professor at the Center for Infectious Diseases and Vaccine Research at the La Hoya Institute of Immunology, added, "We have not observed any evidence that T-cells promote cytokine storms, which are more likely to be mediated by the innocinated immune system."
WHEN SARS-CoV-2 (or any other virus) invades the body, the innate immune system is the first to arrive at the scene and launch a widespread rather than specific attack on the intruder," he said.
it releases a series of signaling molecules that trigger inflammation and alert the precise forces of the immune system to the presence of pathogens.
within a few days, the so-called adaptive immune system will act, attacking invasive viruses with precision, intercepting virus particles and killing infected cells.
adaptive immune system consists of three branches: antibodies; auxiliary T-cells (Ths) that assist B cells in making protective antibodies; and killer T-cells (CTLs) that look for infected cells and destroy them.
in the new study, the researchers collected blood samples from 50 COVID-19 patients and analyzed in great detail all three branches of the adaptive immune system--- SARS-CoV-2-specific antibodies, auxiliary T-cells, and killer T-cells.
"For us, capturing the performance of all diseases, from mild to severe COVID-19, is particularly important so that we can identify differentiated immune factors," said Dr. Sydney Ramirez, co-lead author of the paper and an infectious disease expert who led the collection of blood samples.
" researchers found that, similar to previous studies, all fully recovered patients had measurable antibodies, auxiliary T-cells, and killer T-cell responses, while the adaptive immune response in acute COVID-19 patients varied widely: some lacked neutral antibodies, others lacked auxiliary T-cells or lethal T-cells or any combination of both. "When we analyzed all the data from all 111 measurement parameters, we found that, in general, people who initiated a broader and well-coordinated adaptive immune response tended to perform better," said Dr. Carolyn Moderbacher, co-lead author of the
paper and a postdoctoral fellow at the La Hoya Institute of Immunology.
, a strong SARS-CoV-2-specific T-cell response can predict lighter diseases.
who do not have a coordinated immune response tend to have poor results.
the effects were magnified when the researchers decomposed the data sets by age.
"People over 65 are more likely to have a poor T-cell response and a poorly coordinated immune response, resulting in a more severe or fatal COVID-19," Crotty said.
, part of the greater susceptivity of older people to COVID-19 appears to be a weaker adaptive immune response, possibly because older people have fewer initial T cells (naïve T cells).
" initial T-cells have not yet encountered the virus, but are waiting to be called.
as we age, the supply of initial T-cells that the immune system can deploy decreases, and the number of initial T-cells that can be activated to respond to new viruses decreases.
Moderbacher said, "This can lead to delayed adaptive immune responses that cannot control viral infections, and it is too late to prepare for control, so it is not possible to limit the severity of the disease, or the intensity of the adaptive immune response produced is not sufficient."
" is consistent with previous findings by other research teams that antibodies do not appear to play an important role in controlling acute COVID-19.
, in particular, killer and auxiliary T cells are associated with protective immune responses.
Crotty said, "It's confusing for a lot of people, but controlling primary infections is different from vaccine-induced immunity, where the adaptive immune system is ready to attack from the start."
if the vaccination is successful, the vaccine-induced antibodies are ready to stop the virus when it appears at the door," he said.
, in normal infections, the virus pre-emptions because the immune system has never seen anything like it.
during primary infection, when the adaptive immune system is ready, the virus has replicated within the cell and antibodies cannot reach it in time.
!--/ewebeditor:page--!--webeditor:page title"--Crotty said, "So these results suggest that T cells seem to be more important in natural SARS-CoV-2 infections, and antibodies are more important in COVID-19 vaccines, but T-cell responses to this virus are important in both cases, and that makes sense."
" (bioon.com) Reference: 1. Carolyn Rydyznski Moderbacher et al. Antigen-specific adaptive immunity to SARS-CoV-2 in acute COVID-19 and associations with age and disease severity. Cell, 2020, doi:10.1016/j.cell.2020.09.038.2.T cells take the lead in controlling SARS-CoV-2 and reducing COVID-19 disease severity.