Standard methods to assess T cells may help unravel mysteries

New Delhi : Since immunity against the novel coronavirus is contributed by both the antibodies and cells of the immune system, simpler, standardised lab tests to assess the T cell response in COVID-19 patients may help unravel more mysteries about the disease, say scientists.

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. "So, CD8 T cell responses can kill virus-infected cells of the body and limit virus growth.