Vaccinating against a particular disease-causing microbe triggers the production of memory CD8+ T-cells—immune cells that confer long-term protection against a later infection by that pathogen: After detecting the pathogen, memory CD8+ T-cells proliferate and kill pathogen-infected cells, eliminating that microbe and protecting the host. But it wasn’t known how memory CD8+ T-cells were also able to quickly protect vaccinated people at very early stages of infection.

In a study published online on September 1 in Science Advances, a team led by Gregoire Lauvau, Ph.D., found that memory CD8+ T-cells also send chemical signals, known as cytokines and chemokines, to monocytes—another type of immune cell. One cytokine, interferon gamma, was found to not only activate the monocytes but to modify them as well, making them more responsive to chemokine signals sent later by the memory CD8+ T-cells. These insights into CD8+ T-cell activity could allow scientists to selectively activate an immune response, possibly leading to infection control without the need for pathogen-specific vaccines.

Dr. Lauvau is professor of microbiology & immunology at Einstein. The study’s first author is Marie Boutet, Ph.D., an associate in microbiology & immunology at Einstein.