Interesting - Fetal immune system arises from an entirely different source

[Guest guest]

From: Majid Katme <akatme@...>

not sure why article is titled what it is - not exactly a good title

Sheri

Researchers Find New Source Of Immune Cells During

Pregnancy(Medicalnewstoday)

Main Category:

Immune

System / Vaccines

Also Included In:

Pediatrics

/ Children's Health;

Pregnancy /

Obstetrics;

Infectious Diseases / Bacteria / Viruses

Article Date: 20 Dec 2010 - 0:00 PST

email to a friend

printer friendly

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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 Science.

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 ph 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.

Notes:

Co-authors of the study include Trevor D. Burt, M. ,

Sofiya Galkina and co-senior author Cheryl A. Stoddart, all from the UCSF

Department of Medicine, Division of Experimental Medicine; Jakob

sson, from the Center for Infectious Medicine, Karlinska

Institutet, Stockholm, Sweden; and Shivkumar Venkatasubrahmanyam and

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.

Source:

Bole

University of California - San Francisco

Sheri Nakken, R.N., MA, Hahnemannian

Homeopath

Vaccination Information & Choice Network, Washington State, USA

Vaccines -

http://vaccinationdangers.wordpress.com/ Homeopathy

http://homeopathycures.wordpress.com

Vaccine Dangers, Childhood Disease Classes & Homeopathy

Online/email courses - next classes start December 2 & 3, 2010 and

January 6 & 7

[Guest guest]

From: Majid Katme <akatme@...>

not sure why article is titled what it is - not exactly a good title

Sheri

Researchers Find New Source Of Immune Cells During

Pregnancy(Medicalnewstoday)

Main Category:

Immune

System / Vaccines

Also Included In:

Pediatrics

/ Children's Health;

Pregnancy /

Obstetrics;

Infectious Diseases / Bacteria / Viruses

Article Date: 20 Dec 2010 - 0:00 PST

email to a friend

printer friendly

opinions <?xml:namespace prefix = fb />

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 Science.

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 ph 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.

Notes:

Co-authors of the study include Trevor D. Burt, M. ,

Sofiya Galkina and co-senior author Cheryl A. Stoddart, all from the UCSF

Department of Medicine, Division of Experimental Medicine; Jakob

sson, from the Center for Infectious Medicine, Karlinska

Institutet, Stockholm, Sweden; and Shivkumar Venkatasubrahmanyam and

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.

Source:

Bole

University of California - San Francisco

Sheri Nakken, R.N., MA, Hahnemannian

Homeopath

Vaccination Information & Choice Network, Washington State, USA

Vaccines -

http://vaccinationdangers.wordpress.com/ Homeopathy

http://homeopathycures.wordpress.com

Vaccine Dangers, Childhood Disease Classes & Homeopathy

Online/email courses - next classes start December 2 & 3, 2010 and

January 6 & 7