Survivors of COVID-19 are prone to long-term impairment of lung function. Researchers think that a T-cell-targeted treatment strategy could help.

A new study offers one explanation for why older people may be more susceptible to lung inflammation and fibrosis following viral infection. By studying aged mice, Mayo Clinic researchers found that T cells that reside in tissues—as compared to circulating T cells—were defective after influenza infection. Rather than being protective, these T cells in old animals contributed to inflammation, according to findings published in Science Immunology.

The researchers argued that the discovery could help guide a T-cell-targeted treatment strategy for elderly patients with chronic lung disease after viral pneumonia, including COVID-19.

The culprit T cells are called tissue-resident memory CD8+ T cells, or TRM cells. Instead of circulating in the body, they occupy tissues at portals where pathogens can enter, such as the skin, the lung and gastrointestinal tract. That’s where they ramp up a response once they reencounter a pathogen that they have previously memorized.

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