(Press-News.org) 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 naïve 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.
INFORMATION:
Co-authors of the study include Trevor D. Burt, Jose M. Rivera, Sofiya Galkina and co-senior author Cheryl A. Stoddart, all from the UCSF Department of Medicine, Division of Experimental Medicine; Jakob Michaelsson, from the Center for Infectious Medicine, Karlinska Institutet, Stockholm, Sweden; and Shivkumar Venkatasubrahmanyam and Kenneth Weinberg, of the Center for Biomedical Informatics Research and Division of Hematology/Oncology, respectively, at Stanford University, Palo Alto, Calif. Burt also is affiliated with the UCSF Division of Neonatology in the Department of Pediatrics.
Support for this work was provided by grants from the National Institutes of Health and from the Harvey V. Berneking Living Trust. The authors report no conflicts of interest in this research. Further information can be found in the full paper at www.sciencemag.org.
UCSF is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. For more information, visit www.ucsf.edu.
Accompanying scientific commentary: http://www.sciencemag.org/content/330/6011/1635.full.html
Follow UCSF on Twitter at http://twitter.com/ucsf
UCSF team finds new source of immune cells during pregnancy
2010-12-17
ELSE PRESS RELEASES FROM THIS DATE:
Colossal fossil: Museum's new whale skeleton represents decades of research
2010-12-17
ANN ARBOR, Mich.---There's a whale of a new display at the University of Michigan Exhibit Museum of Natural History, a leviathan that represents a scientific saga of equally grand proportions.
A complete, 50-foot-long skeleton of the extinct whale Basilosaurus isis, which lived 37 million years ago, now is suspended from the ceiling of the museum's second floor gallery and will reign over an updated whale evolution exhibit scheduled to open in April 2011.
"It's a spectacular fossil," said Exhibit Museum director Amy Harris. "Basilosaurus looks ferocious with its big ...
Xlibris Newest Audio Book Publishing Service Changes The Story Telling Game
2010-12-17
Xlibris Publishing, a leader in the self publishing industry, recently announced the latest addition to their self publishing services, the Xlibris Audio Book Publishing Packages. Whatever type of published book the author has, he can now share it to the world as a first-class audio book.
Available in five different services, Touchstone, Compact, Amplified, Storytale and Paramount, the Xlibris Audio Publishing Service produces a digital version of an audio book for the author while the high end packages involve digital availability of the author's books through Overdrive ...
New UK research shows 80% of people avoid paper based directories when looking for tradespeople
2010-12-17
New independent research carried out by Local Traders in the UK has shown that more than 60% of people use online services to find tradespeople than traditional directories, and as many as 80% won't use a paper based phone directory to aide their search.
Results from research conducted at the start of December has shown that the majority of people are turning to the internet and online services when they need to find tradespeople to carry out work on their homes.
2000 people living in the UK were surveyed in the recently conducted independent research, carried out ...
Tarpaflex Refurbishes its Customer Service Levels
2010-12-17
Tarpaflex, an internet based tarps ( http://www.tarpaflex.com ) company, specializes in providing seven popular qualities of tarps online and has been successfully established as a widely known Tarpaulin company for 25 long years now. The latest client for Tarpaflex being the 2012 Olympic stadium in London for their exquisite blue tarps, Tarpaflex has come a long way in spreading its brand name with top notch clients and pride themselves in being one of the rare family owned and operated company as worthy competitors to their larger business contemporaries.
Tarpaflex ...
Stories to Tale announces publication of inaugural two children�EUR s titles.
2010-12-17
Stories to Tale, an independent publishing company announces inaugural publication of two childrens fantasy titles: Christmas in Kangaroo Land by Adla M. Hannon, and Abnora's Quest by Rebekah Cohen, both available from Amazon.com.
Christmas in Kangaroo Land is a charming and imaginative Christmas tale (http://www.amazon.com/Christmas-Kangaroo-Land-Adla-Hannon/dp/0982436300). While delivering presents across Australia, Santas sleigh breaks down, and in order not to disappoint Australias children on Christmas morning, a group of mama kangaroos come forward to deliver the ...
New York Guest joins BlogTalkRadio host Raquel Segura on "AiresLibre Travel Show" December 27, 2010, at 3:00 p.m. Eastern
2010-12-17
Richard J. Williams, CEO of New York Guest, a multifaceted hospitality company that provides services to individuals, wholesale travel partners, hotel companies, corporations and groups will appear on BlogTalkRadio's "AiresLibre Travel Show" with host Raquel Segura on Monday, December 27, 2010, at 3:00 p.m. Eastern.
This episode entitled "Escaping The Postcard Travel Syndrome: New York City" marks the first in the "Escaping the Postcard Travel Syndrome: Spotlight City" series. This series is aimed at educating the average traveler on experiencing the true culture and ...
Golden Spot Launched Low Cost Wire Mesh Welding Machine, Suitable for Precise Wire Mesh Making
2010-12-17
Golden Spot Wire Mesh Welding Machine GSA-80 is equipped with precise Spot Welding System, which helps to adjust the up cylinder, the electrodes, and the fixture based on wire pitch, and this system also can set the welding time and current strength for every individual spot. GSA-80 Auto wire mesh welding machine has auto wire load carriage with wire hopper, which is for loading pre-cut wires. The system will not only automatically feed and collect wires, but also can make the perfect pull-out wire quantity and length as your request. Furthermore, this auto welding machine ...
CanopyHR Solutions Reviews the Top 10 Human Resources Trends of 2010
2010-12-17
This tumultuous year in business has transformed human resources strategies in organizations of all sizes. From its vantage point at the forefront of these HR trends, CanopyHR Solutions, an innovative human resources group based in Orange County, California, offers up its insights on 2010's trends and how some will continue to reshape the way successful businesses operate in 2011.
"Challenging times inspire creative solutions, and the volatile economy has forged many changes in the human resources sector," says Jeff Fenster, founder of CanopyHR Solutions. "Businesses ...
Christmas Traditions For Kids Given To Foster Children by Cherish The Children
2010-12-17
Christmas traditions for kids (http://www.cherishthechildren.org) presented to Pinellas County foster children by Cherish The Children in their 22nd annual holiday event on December 4th. 280 of Pinellas County's Foster Children plus their foster parents attended the Christmas celebration held in the Clearwater Academy International gymnasium.
While the children ate snacks and played on Clearwater Academy's swing set and jungle gym the foster parents picked up the gifts to be wrapped and placed under their Christmas trees - including stuffed animals from Build-A-Bear, ...
GIA Asia Continues to be a Great Place to Work According to 2011 Vault Survey
2010-12-17
Global Intelligence Alliance (GIA), has been recognized by Vault as one of the top Consulting Firms in the Asia Pacific region. GIA Asia was placed eleventh overall in the annual ranking, ahead of McKinsey, BCG, Accenture, Deloitte, KPMG and 14 other companies.
The strategic market intelligence and advisory group also retained a place in the top three in categories such as Diversity for women, Hours in the office, Interaction with clients, Relationship with supervisors, Work/Life Balance and Travel requirements.
"2010 has been a tremendous year of growth for GIA. In spite ...