When antibodies weaken: the role of T cells in the fight against COVID-19

Antibodies have become a familiar concept in the era of pandemic, suggesting that it is the best way of taming the deadly coronavirus. But when was recently published important data about vaccines from COVID-19, the focus was the unsung player of the immune T-cells. This tells Bloomberg.

Когда антитела ослабевают: какую роль играют T-клетки в борьбе с COVID-19

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Companies AstraZeneca Plc, Pfizer Inc. BioNTech and SE, as well as Chinese CanSino Biologics Inc. welcomed the presence of these cells in vaccine recipients as a sign that their experimental test result.

T cells or T lymphocytes, are a reminder that the body’s defenses rely on more than one weapon, and that a large part of the immune response to COVID-19 still remains a mystery — especially after researchers discovered that the much-vaunted antibodies no stamina.

“Antibodies are only a small part of the picture, said Paul Griffin, associate Professor of medicine at the University of Queensland in Brisbane, which leads in Australia clinical studies of two potential vaccines against COVID-19. But we really haven’t reached the goal of full understanding of the immunity of people to the new coronavirus”.

First, scientists have focused on antibodies — proteins that attach to foreign organisms and block them — because their identification is the basis for most successful vaccines. Immune proteins are also easier to measure than T cells and can be used to evaluate already infection.

A study showing that patients with a mild form of the disease the number of antibodies decreases rapidly, undermined the hope that the antibodies will provide some long-lasting form of immunity.

The unsung soldiers

T cells, in contrast, are able to kill virus-infected cells “remember” the disease for decades, and awaken new antibodies to fight the virus after a long time after the first antibody has already left the “battlefield”. For example, people infected with the coronavirus that caused SARS in 2003, still have the T-cell response to the disease 17 years later.

This suggests that T cells, at least hypothetically, may be willing to protect the survivors from SARS, almost two decades later from the same infection, and increase their protection from COVID-19, said Griffin.

“They can be a bit more reasonable shape or a shorter duration of illness, but I certainly don’t think it will protect fully,” he said.

One study showed that some patients without symptoms COVID-19 was the T-cells that recognize virus — even when they did not detect antibodies. Another indicated a certain level of immunity in people who have never faced the current strain of coronavirus: possible, due to the impact of one or several long-known coronaviruses that cause colds.

The necessary balance

More research is needed to determine whether it is possible to explain reaction of T cells to the virus found in some patients with COVID-19 almost do not experience symptoms while others are severely ill and even die. According to Griffin, it is clear that for optimal protection necessary balance as antibodies and T-cells.

Corey Smith, head of immunology at Medical research Institute QIMR Berghofer in Brisbane, said the conclusions about the short life span of antibodies do not mean immunity completely disappears, it is due to the presence of T cells.

The so-called T-helper cells and T – and B-memory cells capable to induce primary production of antibodies to respond to infection before it caused serious symptoms, said Smith, who studies the immune response to the virus SARS-CoV-2.

According to Smith, the current virus, like other coronaviruses that cause colds, can evade the antibodies that leads to a re infection.

“But cellular immunity is sufficient to suppress any serious symptoms,” — said the expert.

Perhaps the T cells eventually suppress and dull the pandemic virus, which has killed more than 600,000 in less than seven months.

“If we can’t eradicate it, whether it will be something like the circulating virus, another virus of the common cold? — says Smith. — I’m not sure, but it’s fun.”

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