What is T-cell immunity system

 What is T-cell immunity system

What are T-Cells?

Like B cells, which produce antibodies, T cells are central players in the immune response to viral infection.

For your immune system to fight off any kind of invader, such as a virus, you need a kind of white blood cell called a B cell, which makes antibodies, and a similar-looking white blood cell called a T cell.

T cells can play different roles altogether.

They can act as "killer cells", attacking cells which have been infected with a virus or another kind of pathogen, or they can act as "helper cells" by supporting B cells to produce antibodies.

How do they function?

Alongside antibodies, the immune system produces a battalion of T cells that can target viruses.

Some of these, known as killer T cells (or CD8+ T cells), seek out and destroy cells that are infected with the virus.

Others, called helper T cells (or CD4+ T cells) are important for various immune functions, including stimulating the production of antibodies and killer T cells.

T cells do not prevent infection, because they kick into action only after a virus has infiltrated the body. But they are important for clearing an infection that has already started.

In the case of COVID-19, killer T cells could mean the difference between a mild infection and a severe one that requires hospital treatment.

What did the latest research find?

The researchers found that neutralising antibodies were detectable even 12 months after infection in "most individuals".

It remained stable 6-12 months after initial infection in people younger than 60 years.

The researchers found that "multifunctional T cell responses were detected for all SARS-CoV-2 viral proteins tested".

And most importantly, the magnitude of T cell responses did not show any difference immaterial of how severe the disease was.

While the ability of antibodies to neutralise was nearly absent against the Beta variant, it was reduced in the case of the Delta variant.

Neutralizing antibodies

SARS-CoV-2-specific neutralising antibody and T cell responses were retained 12 months after initial infection.

Neutralising antibodies to the D614G, Beta, and Delta were reduced compared with those for the original strain, and were diminished in general.

Memory T cell responses to the original strain were not disrupted by new variants.

The findings show that robust antibody and T cell immunity against SARS-CoV-2 is present in majority of recovered patients 12 months after moderate-to-critical infection.

Robustness of antibodies

The study reveals the durability and robustness of the T cell responses against variants, including Delta, even after one year of infection.

Most importantly, the robust and longstanding T cell responses were seen in people who have not been reinfected or vaccinated.

This would mean even in the absence of vaccination, a person who has been infected by the virus even one year ago would have robust immune responses.

It would offer protection against disease progressing to a severe form requiring hospitalization