Antibodies are not the body’s only weapons against the coronavirus. The body also has special immune cells in the lung that can be reactivated more easily than previously thought, according to new research from Salk immunobiologists.
Scientists say these cells could potentially help the body develop long-term immunity against respiratory diseases like SARS-CoV-2. The research is published in the Journal of Experimental Medicine.
T cells are white blood cells that flare up when the body is infected with a virus. They attack the cells that are already infected and get rid of them, so the body can stay healthy, says Salk immunobiologist Susan Kaech.
“When these T cells see the bits and pieces of the virus, that actually activates them. And then they have the ability to expand and multiply,” Kaech said. “They also have the ability to develop new weapons they can deploy to try to suppress the pathogen from replicating inside ourselves.”
The lung is where respiratory disease, like coronavirus, can thrive. Kaech and her team have been studying how easily T cells can be reactivated in the lung once the body has already been exposed to a pathogen.
In studies of the influenza virus in mice, Kaech and her team saw that T cells in the lung could recognize the virus again and be re-activated more easily than previously thought.
“At first, our results were disappointing because it didn’t seem like our experiments were working; the killer memory T cells in the lungs continued to recognize the virus after the deletion of many different messenger cell types,” said Jun Siong Low, another researcher on the study and now a postdoctoral fellow at the Institute for Research in Biomedicine at the Università della Svizzera Italiana in Switzerland.
“Soon, we realized that these lung-resident killer memory T cells were special," he said.
“There are T cells, specifically these memory T cells that are able to live for a long period of time after the first infection and can live for a long time in our lungs,” Kaech said.
T cells in other parts of the body are currently being used in some treatments for diseases like blood cancer. But they still aren’t widely used.
Now Kaech and her team are focusing on how lung memory T cells form in the lung and whether they could be safely used in vaccine design for respiratory diseases like COVID-19.
“A lot of the vaccines that we get such as the childhood vaccines ... the protection they provide are largely based on antibodies,” she said. “But in some cases, we know the antibodies may not be enough.”
Kaech says it’s important to use a mixture of tools against coronavirus. She said one major limitation for using killer T cells is that they can have some negative side effects like killing too many cells or damaging tissue in the body.
She says it’s important to do more studies on how these cells form in the first place and how to harness their power effectively.
