This cellular memory is the basis for how vaccines work. Boosting cellular memory to recognize tumors could help improve cancer therapies.

The research, supported by the National Institutes of Health and published recently in Nature Communications, suggests a new strategy for the next generation of cancer-fighting immunotherapies.

"Imagine that the human body is a fortress," says Leonid Pobezinsky, associate professor of veterinary and animal sciences at UMass Amherst and the paper's senior author, along with a research assistant professor Elena Pobezinskaya.

Our bodies have T-cells, which are white blood cells that specialize in fighting both pathogens, think of the common cold, and altered cells of the organism itself, like tumor cells. Most of the time, the T-cells are "naïve"—mustered out of duty and resting. But when they recognize foreign antigens after bumping into them, they suddenly wake up, turn into killer T-cells and attack whatever the pathogen may be, from the sniffles to COVID, or even cancer.

After the killer T-cells have won their battle, most of them die.

"But," said Pobezinsky, "somehow a few survive, transform into memory cells and form an elite task force called the 'memory pool'—they remember what that particular antigen looked like, so that they can be on the lookout for the next time it invades the body."

This is one of the mechanisms behind how vaccines work: infect the body with a weakened dose of a pathogen—say, the chicken pox virus—and the memory cells will remember what that virus looks like, turn into killer T-cells, annihilate the virally infected cells and then transform back into memory cells, waiting for the next time the chicken pox virus shows up.