A red light for the immune system

WHEN A bug threatens to make you sick, your immune system typically swings into action to deal with the threat. But it’s also important to call off the immune troops when the threat has gone.

Scientists at Trinity College Dublin have identified a new “stop signal” for shutting down a segment of the immune system after infection, and they believe their discovery might help to make tricky vaccines more useful in the future.

The red light is a protein called TMED7, explains Dr Anne McGettrick, a senior postdoctoral fellow in Prof Luke O’Neill’s lab at the Trinity Biomedical Sciences Institute.

At first, the researchers thought TMED7 might be a “go” signal for the immune system, but as they knocked down TMED7 in human cells they realised it functions as a brake.

"It's a way of regulating the immune system, of stopping it when it has done its job," says McGettrick, co-author on a paper out this week in Nature Communications. "If we don't have these stop signals, the immune system will go out of control and start attacking our bodies as well as the bacteria."

It’s not the first stop signal that has been discovered, but it’s another part of the puzzle, according to McGettrick.

“The more we can understand how the immune system works in a healthy person, the more we can understand what is going wrong in a diseased state,” she says.

The study, which was funded by Science Foundation Ireland and the Health Research Board, could point the way to improving responses to vaccines, she adds – some vaccines don’t work well in the body because the immune system doesn’t mount a big response to them.

But if you were to take the TMED7 “brake” off while giving the vaccine, perhaps it could help the body develop immunity, says Dr McGettrick.