A research group led by Shin-ichiro Fujii of the RIKEN Center for Integrative Medical Sciences have found that individuals with a certain human leukocyte antigen (HLA) type may be able to mount a killer T cell response to COVID-19, thanks to the T cells responding to a portion of SARS-CoV-2’s spike protein that is also present in seasonal coronaviruses that cause the common cold.
This work, published in Communications Biology, could help explain the different responses between populations. Up until now, most researchers have focused on the antibody response to SARS-CoV-2, which prevents initial infection.
However, once the virus infects cells, to eliminate viruses quickly, effector lymphocytes—NK cells or memory T cells—become critical. Based on the consideration that NK cell response should be relatively similar across people, they decided to focus on memory killer T cells, which lead an attack against viruses that they “remember.”
T Cells Come to the Rescue as New Studies Show They Remain Highly Effective Against Omicron
An unsung arm of the immune system appears to protect against the Omicron variant even when antibodies wane, helping to explain why a record wave of new COVID-19 cases hasn’t engulfed hospitals or led to high deaths so far.
New findings in separate studies from Erasmus University in the Netherlands and the University of Cape Town in South Africa could help explain why the wave of Omicron cases hasn’t so far caused a surge in mortality from South Africa to the U.S. and the U.K.
Unlike antibodies, T cells can target the whole of SARS-CoV-2’s spike protein, which remains largely similar even in the highly mutated Omicron variant.
The Dutch researchers looked at 60 vaccinated health-care workers and found that while their antibody responses to Omicron were lower or nonexistent compared with the Beta and Delta variants, T cell responses were largely unaltered, “potentially balancing the lack of neutralizing antibodies in preventing or limiting severe COVID-19.”
The study from the University of Cape Town’s Institute of Infectious Disease and Molecular Medicine looked at patients who had recovered from COVID-19 or been vaccinated with shots from Pfizer or Johnson & Johnson. They found that 70% to 80% of the T cell responses they assessed held up against Omicron.