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Standard tests to assess T cells may unravel Covid-19 mysteries: Scientists

Poulomi Sikdar

Scienists and immunologists depending on T lymphocytes for building immunity

Is our body capable enough to protect itself if it is attacked by an infected virus?

Everybody is not capable to fight with virus in the same way. To know how much can a body can protect is itself is known through its immunity. This immunity is chiefly maintained by T-Lymphocytes.

Now, how can we know by how much a T Lymphocyte is capable of fighting? This method is invented by two Medical scientists and their invention has shown a new way in the Covid war.

The two Medical scientists are Dr. Sonali Asthana and Dr. Vishnu Kurpad. They have created a buzz due to the invention of the method of calculating T Lymphocyte capability to fight.

How can one know that?

The answer is through a blood test. Through a blood test named Invitro Culture. The Covid antigen is excited and under Elisa test method, it will be seen how much the T cell will release Cytokine, an interferon gamma.

Generally, whether a person would or would not be attacked by a virus depends on this T Lymphocyte. The intensity of a virus attack also depends on the amount of Cytokine emitted by this T Lymphocyte. Scientists believe if the function of T cell, rather the amount of emission of Cytokine by T Lymphocyte is measured, then we will be able to know how much a body is capable of protecting itself when attacked by coronavirus.

Basically, whether a person would be symptomatic carrier or asymptomatic career of Covid, also depends on this T Lymphocyte. Scientists believe, if the ability of T Lymphocyte to resist a body from the attack of virus is known, then half if the work is easily done. A patent has been submitted for this. If the proposal is accepted, then the process for making the kit will start.

When the Covid pandemic started many people told about Herd Immunity. But, later on this idea was criticized by many scientists. Many researches ultimately showed that personal immunity is the only and primary way for what could be the future of Covid. Scientists claimed that the finding of Dr.Sonali Asthana and Dr. Vishnu Kurpad firmly holds the belief on the new method.

Though Invetro Culture test is not happening for the first time. Previously, this 'Gamma Interferon Release Assay' was practiced for Tuberculosis, Cytomegalovirus, Harpic Jester and for many other diseases. "This is for the first time, this 'Gamma Interferon Release Assay' was used," Virologist, Dr. Siddhartha Joyardar said.

The diagnostic centers do not have any special equipment, to measure the capability of T Lymphocyte. What they have is the kit which can be used to measure antibodies. By measuring antibodies, we can get the idea, whether a person is affected by COVID-19 or not. But the problem is that to protect oneself from Covid, only antibody is not enough. Another important factor is played by T Lymphocyte Cell.

Immunologist Satyajit Rath noted that the two major components of immunity specific for any infection are the T cell responses, and those mediated by the immune system's B cells along with the antibody proteins they produce.

"Antibody responses are easier to measure, especially on a large scale, and they have traditionally been the protective components of vaccine-induced immunity. Therefore, they always tend to be focused upon, as is true in the ongoing pandemic as well," Rath, from the National Institute of Immunology (NII) in New Delhi, told PTI.

T cell responses, he added, while also "very important," are "technically much harder to study, particularly in human communities."

According to Rath, a subset CD8 T cells provide a major anti-viral immune function which may have a substantive role to play, especially in people whose antibody responses turn out to be short-lived.

Daniel Altmann, Professor of Immunology at the University College London in the UK, agreed with Rath.

"One of the best indicators of the importance of T cell immunity comes from reports of people who have made full recovery from Covid 19 despite the complete absence of antibodies," he told PTI.

Another subset of the T cells -- called CD4 T cells -- help the B cell-antibody response become more efficient and long-lived, Rath noted, adding that these must be examined in order to understand the efficiency and longevity of antibody responses.

According to the NII immunologist, CD4 T cell responses also contribute anti-viral functions as well as causing tissue and organ damage.

 

Not only in India, but news of repeated attacks were heard from different countries. So there's a question on the future of Covid survivors. They are not safe. Many researchers have proved that the duration of antibodies in the body of a covid survivor is maximum two to three months. In many instances, antibodies are disappearing even faster. This problem is even severe for the asymptomatic carriers of Covid.

Rath agreed that there is a need to develop standardised tests to assess the T cell response in Covid-19 patients across the severity spectrum. While some existing kits have been developed for evaluating the CD4 T cell response to bacterial infections, he said Covid-19 may need assessment of CD8 T cell as well.

"These may be more difficult to develop as commercial tests. So multiple tests may well be needed, and they will all need much validation," Rath added.

Also Read: Covid-19 antibodies can disappear in month: Is that a Concern?

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