Immunity system complexity: lung proteins call for T cells (Introduction)

by David Turell , Friday, September 27, 2019, 15:24 (1884 days ago) @ David Turell

Special complex lung proteins signal for T cell help:

https://medicalxpress.com/news/2019-09-immunologists-cell-homing-beacons-lungs.html

"Scientists have identified a pair of molecules critical for T cells, part of the immune system, to travel to and populate the lungs.

"CD8 T cells, which survey other cells for signs of viral infection and kill infected cells, are an important arm of our defenses too. The epitopes—or bits of viral protein—they recognize generally do not change from year to year.

"Researchers led by Jacob Kohlmeier, Ph.D., at Emory University School of Medicine wanted to learn more about what's needed to get CD8 T cells into the lungs, since the lungs will often contain the first cells incoming virus will have a chance to infect. However, T cells don't stick around in the lungs for extended amounts of time.

"'The airways are a unique environment in the body," says Alex Wein, a MD/Ph.D. student who trained in Kohlmeier's lab. "They're high in oxygen but low in nutrients. Unlike other tissues, when T cells enter the airways, it's a one-way trip and they have a half-life of a few weeks, so they must be continually repopulated."

***

"The researchers showed that two molecules, called CXCR6 and CXCL16, are needed for CD8 T cells to reach the airways in mice. CXCR6 is found on T cells and CXCL16 is produced by the epithelial cells lining the airways of the lungs.

"Other molecules necessary for T cells to home to the intestines or the skin were already known. The lungs have been more difficult to study because of how many blood vessels run through them. Recently, scientists have been able to discern two distinct populations of lung T cells, present in the interstitium—between the lung epithelial cells and blood vessels—and others in the blood.

"CXCR6 is a homing beacon that allows T cells to travel through the lung interstitium and into the airways.

***

"Most of the experiments used mice, but the researchers did show that CXCR6 was abundant on CD8 T cells in the lungs of humans as well. CXCL16 is also made by the airway epithelium in humans. "

Comment: Another specialized protein designed with purpose to protect the lungs. Not by chance.