Navigation Links
UCSF team finds new source of immune cells during pregnancy
Date:12/16/2010

UCSF researchers have shown for the first time that the human fetal immune system arises from an entirely different source than the adult immune system, and is more likely to tolerate than fight foreign substances in its environment.

The finding could lead to a better understanding of how newborns respond to both infections and vaccines, and may explain such conundrums as why many infants of HIV-positive mothers are not infected with the disease before birth, the researchers said.

It also could help scientists better understand how childhood allergies develop, as well as how to manage adult organ transplants, the researchers said. The findings are described in the Dec. 17 issue of Science and at www.sciencemag.org/content/330/6011/1695.full.html.

Until now, the fetal and infant immune system had been thought to be simply an immature form of the adult system, one that responds differently because of a lack of exposure to immune threats from the environment. The new research has unveiled an entirely different immune system in the fetus at mid-term that is derived from a completely different set of stem cells than the adult system.

"In the fetus, we found that there is an immune system whose job it is to teach the fetus to be tolerant of everything it sees, including its mother and its own organs," said Joseph M. McCune, MD, PhD, a professor in the UCSF Division of Experimental Medicine who is a co-senior author on the paper. "After birth, a new immune system arises from a different stem cell that instead has the job of fighting everything foreign."

The team previously had discovered that fetal immune systems are highly tolerant of cells foreign to their own bodies and hypothesized that this prevented fetuses from rejecting their mothers' cells during pregnancy and from rejecting their own organs as they develop.

The adult immune system, by contrast, is programmed to attack anything it considers "other," which allows the body to fight off infection, but also causes it to reject transplanted organs.

"The adult immune system's typical role is to see something foreign and to respond by attacking and getting rid of it. The fetal system was thought in the past to fail to 'see' those threats, because it didn't respond to them," said Jeff E. Mold, first author on the paper and a postdoctoral fellow in the McCune laboratory. "What we found is that these fetal immune cells are highly prone to 'seeing' something foreign, but instead of attacking it, they allow the fetus to tolerate it."

The previous studies attributed this tolerance at least in part to the extremely high percentage of "regulatory T cells" those cells that provoke a tolerant response in the fetal immune system. At mid-term, fetuses have roughly three times the frequency of regulatory T cells as newborns or adults, the research found.

The team set out to assess whether fetal immune cells were more likely to become regulatory T cells. They purified so-called nave T cells new cells never exposed to environmental assault from mid-term fetuses and adults, and then exposed them to foreign cells. In a normal adult immune system, that would provoke an immune attack response.

They found that 70 percent of the fetal cells were activated by that exposure, compared to only 10 percent of the adult cells, refuting the notion that fetal cells don't recognize outsiders. But of those cells that responded, twice as many of the fetal cells turned into regulatory T cells, showing that these cells are both more sensitive to stimulation and more likely to respond with tolerance, Mold said.

Researchers then sorted the cells by gene expression, expecting to see similar expression of genes in the two cell groups. In fact, they were vastly different, with thousands of genes diverging from the two cell lines. When they used blood-producing stem cells to generate new cell lines from the two groups, the same divergence occurred.

"We realized they there are in fact two blood-producing stem cells, one in the fetus that gives rise to T cells that are tolerant and another in the adult that produces T cells that attack," Mold said.

Why that occurs, and why the immune system appears to switch over to the adult version sometime in the third trimester, remains unknown, McCune said. Further studies will attempt to determine precisely when that occurs and why, as well as whether infants are born with a range of proportions of fetal and adult immune systems information that could change the way we vaccinate newborns or treat them for such diseases as HIV.


'/>"/>

Contact: Kristen Bole
kristen.bole@ucsf.edu
415-502-6397
University of California - San Francisco
Source:Eurekalert  

Related medicine news :

1. Second Brain Death Exam Unnecessary, Study Finds
2. Its True: Money Cant Buy Happiness, Study Finds
3. New research finds delaying surgical procedures increases infection risk and health care costs
4. Report Finds Baby Boomers to Gain Most From Health Care Reform
5. Kids Not So Stuck on Sugary Breakfast Cereals, Study Finds
6. Depression drug may relieve pain from breast cancer treatment, U-M study finds
7. Walkable Communities More Close-Knit, Study Finds
8. Critter Crossings Improve Highway Safety, Study Finds
9. Drug combination shows promise for newly diagnosed blood cancer patients, study finds
10. Weight-Lifting After Breast Cancer Wont Cause Lymphedema, Study Finds
11. Surgery complications linked to chemotherapy delay, U-M study finds
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
UCSF team finds new source of immune cells during pregnancy
(Date:6/27/2016)... Overland Park, KS (PRWEB) , ... June 27, 2016 , ... ... leader in retailers of Eyeglasses . , Millions of individuals in the United ... life, eyeglasses have become a way to both correct vision and make a fashion ...
(Date:6/26/2016)... ... 26, 2016 , ... On June 10-11, 2016, A Forever Recovery, a holistic ... World’s Longest Breakfast Table in Battle Creek, MI, where the rehabilitation facility is located. ... some of the world’s leading providers of cereal and other breakfast foods. Its residents ...
(Date:6/26/2016)... North Carolina (PRWEB) , ... June 26, 2016 , ... ... release of a new product that was developed to enhance the health of felines. ... for centuries. , The two main herbs in the PawPaws Cat Kidney Support ...
(Date:6/26/2016)... Clarkston, Michigan (PRWEB) , ... June 26, 2016 ... ... respect to fertility once they have been diagnosed with endometriosis. These women need ... but they also require a comprehensive approach that can help for preservation of ...
(Date:6/25/2016)... TX (PRWEB) , ... June 25, 2016 , ... Austin ... of the American College of Mohs Surgery and to Dr. Russell Peckham for medical ... and highly effective treatment for skin cancer. The selective fellowship in Mohs Micrographic Surgery ...
Breaking Medicine News(10 mins):
(Date:6/23/2016)... 2016 Bracket , a leading clinical trial ... clinical outcomes platform, Bracket eCOA (SM) 6.0, at the ... – 30, 2016 in Philadelphia , Pennsylvania.  ... Assessment product of its kind to fully integrate with RTSM, ... eCOA 6.0 is a flexible platform for electronic clinical outcomes ...
(Date:6/23/2016)... and INDIANAPOLIS , June 23, ... a Lilly Diabetes Tomorrow,s Leaders Scholarship is any indication, ... winners, announced today online at www.diabetesscholars.org by ... 1 diabetes stand in the way of academic and ... the Foundation,s scholarship program since 2012, and continues to ...
(Date:6/23/2016)... , June 23, 2016 ... Oticon , industry leaders in advanced ... launch of Oticon Opn ™, the world,s first ... of possibilities for IoT devices.      (Photo: ... Oticon introduces a number of ,world firsts,: ...
Breaking Medicine Technology: