T cells (T lymphocytes) store information about antigens previously detected by the immune system in the body and form long-term immunity to infectious diseases. There are reports from various countries that T cells specific to SARS-Cov-2 are present even in people who have had the infection asymptomatically and have not developed antibodies. However, it is very difficult to measure cellular immunity: such studies are carried out only in specialized laboratories, almost manually. Meanwhile, data on the presence of cellular immunity are also necessary in order to make a decision on vaccination.
Scientists at the Pasteur Research Institute managed to create a simple and affordable test system that can be used in medical institutions without special equipment, the newspaper Komsomolskaya Pravda reported. To assess cellular immunity, a special artificial antigen to the coronavirus is intracutaneously injected into the patient, after which the reaction is monitored. The formation of papules, as in the Mantoux reaction, means a positive result, that is, the patient has T-cell immunity. The intensity of the immune response is indicated by the size of the resulting swelling, which the healthcare professional measures with a ruler and decides whether to vaccinate.
According to the head of the Pasteur Research Institute, Professor Areg Totolyan, this technology has no analogues in the world and is absolutely safe: the test system does not contain a single component that can lead to infection of the organism with SARS-Cov-2.
Scientists expect to register the test system by the end of 2021, after which it can be massively used in hospitals and clinics.
At the moment, scientists from the National Medical Research Center of Hematology are also developing a test for assessing cellular immunity. The technology is based on a proven method for detecting virus-responsive T cells, but the know-how of Russian specialists consists in a specific set of fragments of coronavirus proteins that are carefully selected, and those that can give a false positive T-cell reaction are cut off. These tests will be able, in controversial cases, to confirm the fact of the transferred coronavirus infection, and also be used to assess the effectiveness of vaccination.