World News – CA – Immune system holds clues about mild or severe Covid reaction


This electron microscope image made available and featured by the National Institute of Allergy and Infectious Diseases Integrated Research Facility in Fort Detrick, Maryland, in 2020 shows particles of the novel coronavirus SARS- CoV-2, orange, isolated from patient One of the scariest mysteries of COVID-19 is why some people are mildly ill or have no symptoms and others die quickly – and scientists are starting to understand why (NIAID / National Institutes of Health via AP)

One of the scariest mysteries of COVID-19 is why some people are mildly ill or have no symptoms and others die quickly – and scientists are starting to understand why

An international team of researchers have found that in some people with severe COVID-19, the body goes rogue and attacks one of its own key immune defenses instead of battling the coronavirus Most were men, this which explains why the virus hits men harder than women

And separate research suggests children fare better than adults because of strong ‘first responder’ immune cells that decline with age

This is the latest in a list of studies revealing multiple features of the complex immune system cascade that may tip the scales between a good or a bad outcome Next step: determine if all these new clues could offer indispensable means of intervention

« We have the knowledge and the ability to really strengthen many aspects of the immune system, but we must not use mass, » warned Dr. Betsy Herold of the Albert Einstein College of Medicine in New York, co- author of the study on children

Adding to the complexity, the extremely variable reactions of people also reflect other factors, such as their initial health and the amount of virus – the « dose » – to which they were exposed

« Infection and what happens after infection is a very dynamic thing, » said Alessandro Sette, a researcher at the La Jolla Institute for Immunology in San Diego, who is studying another element of the response. immune

There are two main arms of the immune system Innate immunity is the body’s first line of defense As soon as the body detects a foreign intruder, key molecules, such as interferons and inflammatory cytokines, launch an attack of great span

Innate immune cells also alert the slower acting ‘adaptive’ arm of the immune system, germ-specific snipers, to prepare B cells begin to produce anti-virus antibodies, proteins hold so attention in the hunt for the vaccine

But antibodies aren’t the whole story The many other ingredients of adaptive immunity include “killer” T cells which destroy cells infected with the virus and “memory” T and B cells which remember  » an infection so that they go into action more quickly if they encounter this germ again

Usually, when a virus invades a cell, proteins called type I interferons kick in, defending the cell by interfering with viral growth.But new research shows these crucial molecules were essentially missing in a subset of people with severe COVID-19

International project discovered two reasons In the blood of nearly 1,000 patients with severe COVID-19, researchers found that one in 10 had what are called autoantibodies – antibodies that attack by mistake virus fighters needed Particularly surprisingly, autoimmune diseases tend to be more common in women – but 95% of those COVID-19 patients were men

In 660 other critically ill patients, the same team found 35% had genetic mutations that did not produce type I interferons

Each of these silent vulnerabilities were enough to tip the scales in favor of the virus early on, said Dr. Jean-Laurent Casanova, infectious disease geneticist at Rockefeller University in New York, who is co-leading the effort. human genetics COVID It is paid for by the Howard Hughes Medical Institute, which also helps fund the Associated Press Health and Science Department

Some interferons are used as drugs and are being studied as a possible treatment for COVID-19; discovery of autoantibodies adds another factor to consider

It’s unclear why children appear less exposed to COVID-19 But sometimes they’re sick enough to be hospitalized, allowing Herold’s team to compare 60 adults and 65 children and adolescents in the healthcare system Montefiore from New York

Children produced much higher levels of certain cytokines which are among the first responders of the innate immune system When the next stage of the immune system began, adults and children made antibodies targeting the coronavirus Here is the catch : the adaptive immune response of adults was more of the type that can trigger an overreaction

The results suggest that the early and robust response of children allows their immune systems to get ahead of the virus, making an overreaction less likely « and it protects them, » Herold said

The coronavirus that causes COVID-19 is new to humans But Sette’s team studied blood samples stored in freezers before the pandemic and found hosted memory T cells that recognized a tiny fraction of the new virus in laboratory tests

« You can actually tell this is an experienced T cell It has seen some fighting before, » Sette said Researchers in Germany, Britain and other countries have made similar conclusions

The novel coronavirus has cousins ​​that cause up to 30% of colds, so researchers believe these T cells could be leftovers from colds from the past

But despite speculation, « we don’t yet know » that having these T cells makes a difference in people who are seriously ill with COVID-19, noted Rory de Vries, co-author of a study in the Netherlands who found such T cells in old blood

All of these findings call for a better understanding of the myriad ways some people may be more vulnerable than others

« We need to take a broad enough view and not jump to premature conclusions about any particular facet of the immune system, » said Bali Pulendran, Stanford University immunologist He also found innate immune cells « in hibernation » in critically ill adults and then looks for differences before and after people get sick.

But, « it’s not just about the immune system, » warned Dr Anita McElroy, a viral immunity expert at the University of Pittsburgh who is closely following research on A Way to Know Beforehand Who is most at risk? « We are very, very far from it »

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Coronavirus, immunity, virus, immunology

News from the world – CA – Immune system holds clues about mild or severe Covid reaction


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