T lymphocytes may bridge the gap in COVID-19 immunity.
Immunity and susceptibility to COVID-19 is an area of ongoing research. Findings from a recent study indicate that T cells that react to the SARS-CoV-2 spike protein are present in both COVID-19 patients and healthy people unexposed to the virus.
T lymphocytes, also known as T cells, are part of the body’s adaptive immune response. T cells are produced when the body encounters a viral, bacterial, or fungal pathogen. T cells come in a variety of forms, including helper T cells, cytotoxic T cells and memory T cells.
Previous research has demonstrated the presence of SARS-CoV-2-reactive T cells circulating in the blood of unexposed people. The current study characterized T cell reactivity against the SARS-CoV-2 spike protein in COVID-19 patients and unexposed people.
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The authors of the study combined isolated immune cells from both COVID-19 patients and unexposed people to synthetic segments of the SARS-CoV-2 spike protein. They found reactive memory T-helper cells in 83 percent of people with COVID-19 and 35 percent of people who had not been exposed to the virus. The T cells of COVID-19 patients reacted to both the N- and the C-terminal ends of the SARS-CoV-2 spike protein. However, the T cells of unexposed individuals reacted primarily to the C-terminal end of the spike protein — a region that shares similarity with “common cold” coronaviruses.
These findings suggest that there is some pre-existing immunity in the general population against SARS-CoV-2, possibly due to exposure to the common cold coronaviruses. Larger studies are needed to determine if cross-immunity will affect the clinical outcomes of COVID-19 patients.
Learn more about COVID-19 in these Q&As featuring Dr. Rhonda Patrick, posted April 14 and June 10.