Our immune system is responsible for fighting the coronavirus... As new evidence emerges about how the body reacts to the coronavirus, we take a look at how different immune cells work together to fight the new coronavirus and the more important role of T cells.

Many people are familiar with the concept of antibodies that the body produces to fight disease.... In the fight against the new corona virus called SARS-CoV-2, scientists have widely pointed to the role of antibodies as the holy grail to neutralize and create immunity against future diseases.

However, antibodies are not produced in a vacuum.... In fact, multiple cells must work together to produce antibodies, especially neutralizing antibodies.

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We need a subset of T cells to carry out the complex interactions that lead to antibody production....Another type of T cell destroys virus-infected cells....We now know that T cells play an important role in providing immunity against Covid-19.

But what is the T cell and why does it play a key role in the fight against the new corona virus?

To understand the role of T cell and its relationship with antibody and short-term and long-term immunity, we must enter the science of immunology.

RoleTWhat are cells?

T cell is a type of lymphocyte or white blood cell.... The bone marrow produces T cells in the form of sample cells and goes to the T gland of the mouse, that's why the name T cell was given to it.

There are different types of T cells.

Dr. John Yodel, who is the Chief of Cell Biology in the Laboratory of Infectious Diseases at the National Institute of Allergy and Infectious Diseases in Bethesda, provided an overview of the role of T cells in Covid-19 in his recent podcast.

Helper T cells, also called CD4 T cells or CD4 helper T cells (because they carry a protein called complex of differentiation 4 (CD4) on their surface), protect the body against pathogens.... Dr. Yodel explains that when a virus infects a cell, there are two ways for the immune system to notify the foreign invader.

After the virus enters the cell, it passes through several parts and enzymes break it into small peptides.

Some of these peptides are attracted to MHC class II molecules.

These molecules are part of the body's tools for survival.

The MHC class II molecules then return to the cell surface and deliver the viral peptide to the cell.... These peptides activate the helper T cell, which plays an important role... producing the virus.

The B cell then becomes a plasma cell or memory B cell in response to the interaction with the helper T cell.. After moving to the bone marrow, the plasma cells produce antibodies for several weeks and remain in the bone marrow for long-term protection.

Memory B cells remain in circulation as part of the body's defense system or reside in important areas... If the body encounters the same virus again, the memory B cells recognize the antigen of the virus, process it, and deliver it to the helper T cell.

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What is the role of killer cellT?

While helper T cell recognizes antigen presented by MHC class II molecule, cytotaxin T cell or CD8 T cell or CD8 killer T cell reacts to peptide presented by MHC class I molecule.

When a virus infects a cell, it hijacks the cell's machinery to make viral proteins... But some of the peptides made in the process are directed to the MHC class I molecule, which takes them to the cell surface and gives them to other cells.

In this way, the cell can show that it is infected with a virus... The CD8 T cell recognizes and destroys infected cells, so it is a key mechanism to get rid of the disease.

Since many viruses replicate very quickly, this process must be done quickly to prevent the virus from spreading... CD8 T cells recognize influenza-infected cells within 1.5 hours with the help of MHC class I molecules that bring the viral peptide to the cell surface.

The CD8 T cell can become a memory CD8 T cell, which reacts quickly when exposed to many similar viruses, and its effect is long-lasting.

CD4 helper T cells and CD8 T cells both play an important role in Covid-19.

In a new paper published in the journal Immunology, researchers from the Institute of Immunology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia summarize the results to date on T cells and Covid-19.

They showed that the CD8 T cell response in people with severe Covid-19 disease is not as effective as in people with mild disease....In particular, the number of CD8 T cells in the body of these people may be lower and those CD8 T cells in their body may not have the ability to transform into CD8 memory T cells.

But they point out that the results of all researches are not included in this example.. Researchers found that in some substances, the reaction of CD8 T cells in the body of patients with Covid-19 was very high.

Data on CD4 helper T cells also show the same pattern of erratic or incorrect natural response.

Xiao Shen and E... John Varry say: "Most hospitalized patients appear to show CD4+ and CD8+ T-cell responses, and the evidence suggests that the T-cell response to this disease is unfavorable, excessive or, in severe cases, inappropriate."

They went on to say: "Actually, the pattern of T cell reaction is different in different patients.. This suggests that we probably need to use a specific treatment method for each individual depending on the type of immune system of each patient."

Antibody test and T cellreaction

In many cases, scientists use antibody tests to determine whether a person's body has reacted to the virus.

This is different from the PCR diagnostic test, which looks for the genetic material of the virus to determine whether a person is currently infected.

Antibody testing is relatively simple and accurate... A new study in Spain used a combination of a fingerstick blood test and a laboratory test to determine how many people in the country have antibodies to SARS-CoV-2 in their bodies.

However, testing people's T-cell responses is not easy.

In a new study, to compare T-cell responses between people who have recovered from Covid-19 and samples taken from people before the pandemic, scientists exposed T-cell precursors in the blood to a viral peptide to see whether CD4 helper T cells or CD8 T cells responded to the virus.

Then, using professional equipment, they identified the different types of T cells that were formed from the raw materials.

Since there is a need for more reliable and faster testing methods to diagnose a person with SARS-CoV-2, scientists are looking for new ways to detect how T cells react to the new corona virus.

Medical News recently interviewed Dr. James Hindley of Inland Biotechnology, who is working on a simple T-cell test that scientists can use in the lab.

Dr.. Hindley explains: "In the first place, we believe that the main use of this test is related to the development of a vaccine to ensure the T-cell response to the vaccine and the adequacy of immunity against the disease."

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He also predicts that the community could use the test to monitor T-cell responses to SARS-CoV-2... This method, together with the antibody test, allows us to determine the level of immunity in the community.

Scientists need more information to explain how T and B cells respond to SARS-CoV-2 long-term in terms of pathology and immunity.

While the scientific community responds to the needs of the pandemic, we hope that new and innovative methods of testing and large-scale research will answer some of these questions.