"We found a specific mechanism that selectively sorts out the best T cells (CD8aa) to become memory T cells at the (mucosal) border," said Dr. Cheroutre. T cells are the body's infection fighting white blood cells. "The immune system has developed a very ingenuous system to make that selection and to ensure that the ones that reside at the (mucosal) border are the fittest T cells."
The mechanism involves interplay between two related molecules, CD8ab and CD8aa expressed by T lymphocytes, and a molecule expressed on interacting cells including the epithelial cells of the intestine. This molecule distinguishes between CD8ab and CD8aa expressing cells and selects the strongest, most effective T cells (CD8aa and CD8ab expressing), by killing off the weaker T cells (CD8ab expressing only).
Dr. Cheroutre noted boosting immune memory cells at the intestines and other mucosal linings could enable the body to stop various pathogens at their primary entry point. "This is very important since many pathogens enter the body through these areas and begin destroying the tissues and the immune system before T cells in other parts of the body can arrive and begin fighting," she said.
She said the finding could have special implications for researchers working to develop an AIDS vaccine. "The scientific community has thought that to induce immunity to HIV, we have to activate the immune system with an antigen (similar to HIV) and generate pre-existing anti-HIV memory cells," she said. "What we did not know, was that there is a special mechanism required to selectively send the most effective immune cells to the mucosal border, which is often where pathogens such as HIV or Listeria enter the body."
Dr. Cheroutre said currently the protective quality of most vaccines is ju
|Contact: Bonnie Ward|
La Jolla Institute for Allergy and Immunology