Navigation Links
UCSF team finds new source of immune cells during pregnancy

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

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
University of California - San Francisco

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:
Related Image:
UCSF team finds new source of immune cells during pregnancy
(Date:11/30/2015)... ... November 30, 2015 , ... ... Centers’ National Poison Data System (NPDS) reveals that in 2014, someone called a ... cases, over two million of which were human exposure cases. , The American ...
(Date:11/30/2015)... ... November 30, 2015 , ... Brenntag Specialties, Inc. ... partner for the Nutraceutical Specialties products into oral solid dosage in the over ... , “We are pleased to announce our expanded distribution agreement with ASI.” said ...
(Date:11/30/2015)... ... November 30, 2015 , ... ... announced at the Radiology Society of North America (RSNA) annual meeting, being held ... 60% growth from 2014. Throughout 2015, the company has completed installations for ...
(Date:11/30/2015)... ... November 30, 2015 , ... Holcomb – Kreithen Plastic ... surgery practices in Florida, is proud to announce that Dr. Joshua Kreithen, one ... Ethicon Inc., a Johnson & Johnson Company. , Ethicon is a global medical ...
(Date:11/30/2015)... (PRWEB) , ... November 30, 2015 , ... ... strategic alliance around Novus’ TIGR® Matrix Surgical Mesh technology for soft tissue repair ... polymers, TIGR® Matrix is a long-term resorbable surgical mesh intended to support and ...
Breaking Medicine News(10 mins):
(Date:11/30/2015)... , Nov. 30, 2015   Royal Philips ... Implant, the industry,s first MRI guided user interface and ... of patients with MR Conditional implants, such as knee ... 2015 Radiological Society of North America Annual Meeting ... and supports diagnostic confidence of this growing patient population. ...
(Date:11/30/2015)... BOCA RATON, Fla. , Nov. 30, ... of Public Research (the Institute) announced today that ... , a medical device start-up company with technology developed ... creation based on publicly-funded research, and bridges early funding ... -based universities and research institutions. ...
(Date:11/30/2015)... Nov. 30, 2015 Baxalta Incorporated ... leader dedicated to delivering transformative therapies to ... conditions, today announced the launch and first ... an extended circulating half-life recombinant factor VIII ... full-length ADVATE [Antihemophilic Factor (Recombinant)]. The treatment ...
Breaking Medicine Technology: