A novel test for T cells show great promise in detecting immune status
Antibodies often steal the spotlight when talking about immunity, but they are not the only protagonist in the immune system.
T cells are specialized defenders activated in the adaptive immune response. They multiply and differentiate into cytotoxic, helper, or regulatory t-cells. These types of lymphocytes are critical in the identification, management, and clearance of infections.
New research shows that T-cells are optimal targets for evaluating immunity to SARSCoV-2 infection because of their critical role in the immune response. Up to this point, we have exclusively focused on the use of serological tests for an indication of prior COVID-19 infection. In the current state, the Food and Drug Administration (FDA) issues emergency use authorization (EUA) to over sixty serology products to detect SARS-CoV-2 antibodies. (1) Antibody testing for COVID-19 on the market may shortly be challenged by a new competitor: a novel test for the detection of T-cells.
Adaptive Biotechnologies, an innovative biotechnology company based in Seattle, in collaboration with Microsoft, has developed a T cell-based clinical test that can detect an immune response to past Covid-19 infections. This test utilizes a unique T-cell signature, developed via identified “shared” T-cell Receptors (TCRs) of multiple infected individuals worldwide. (2) If authorized by the Food and Drug Administration (FDA), TDetect™ would become the first commercial product to detect T cell response to SARSCoV-2. (3)
In a study by Gittelman et al., researchers analyzed T cell and antibody levels in 2,200 individuals from the municipality of Vo, Italy. Vo initially became famous as the location of Italy’s first COVID-19 related fatality. Of the 2,200 samples, 70 were previously collected from confirmed PCR positive patients. TDetect™ identified 97% of (68 of 70) individuals with previously confirmed PCR results, compared to 77% (54 of 70) from a
positive serology test result. Additionally, this study observed more significant T-cell detection in symptomatic versus asymptomatic
patients, whereas antibody levels did not correlate with disease severity. (4, 5)
T cells’ ability to detect the severity of the disease, unlike antibody’s, can offer insight into the reason for a wide range of clinical presentations, from asymptomatic to severe illness or even death of individuals with different backgrounds. This new test may additionally help researchers measure longterm immunity or potential level of protection after infection or vaccination.
Middle East Respiratory Syndrome (MERS) and SARS-CoV-1 infections have previously indicated that coronavirus-specific T cells have long-term effectivity and contribute to protection even in individuals with minimal
antibody production. (6, 7) If this test proves to be specific to COVID-19, a more sensitive method of measuring previous exposure will be available, potentially detecting cases faster and more accurately.
Written by Yesenia Morales