She said the reason vaccines are measured this way is logistical. "Researchers can easily take a blood sample and measure T cell numbers in an individual's blood," she said. "However, we cannot, as a practical matter, measure T cells in the intestines of a living person. So although many vaccines induce effective immune protection, we don't know whether a particular vaccine protects us from viruses and bacteria entering through the mucosal linings because up until now, we didn't have a way to measure pre-existing immunity at mucosal interfaces."
The team found a remedy for that situation by showing that the induction of CD8aa on the immune cells in the blood activated by the vaccine warrants protection at the mucosal borders. "This gives us a means of testing potential vaccines for their protective ability at mucosal borders such as the intestine and other pathogen entry-sites," she said. "Basically, the more CD8aa positive immune effector T cells that are generated by a vaccine, the better the protection at mucosal borders."
Dr. Cheroutre noted that her finding provides information about the mechanism of action for generating mucosal T cell memory, but it remains to be determined how vaccines can be engineered to induce this valuable mucosal immune memory. "This will be the next step for us and for the broader research community," she said. "To provide an effective vaccine, we need to be able to trigger the body to do what the endogenous immune system is doing induce high affinity effector T cells and selectively sort out those cells to reside at the mucosal borders."
The finding represents Dr. Cheroutre's second major discovery o
|Contact: Bonnie Ward|
La Jolla Institute for Allergy and Immunology