Web address:

http://www.sciencedaily.com/releases/2008/10/081026101713.htm  

 

How Breastfeeding Transfers Immunity To Babies

 

BYU microbiology professor Eric Wilson led a research team that included
undergraduates Kathryn Distelhorst (r) and Elizabeth Nielsen Low that showed
how breastfeeding passes mothers' immunity on to babies.\- A
BYU-Harvard-Stanford research team has identified a molecule that is key to
mothers' ability to pass along immunity to intestinal infections to their
babies through breast milk.

 

The study highlights an amazing change that takes place in a mother's body
when she begins producing breast milk. For years before her pregnancy, cells
that produce antibodies against intestinal infections travel around her
circulatory system as if it were a highway and regularly take an "off-ramp"
to her intestine. There they stand ready to defend against infections such
as cholera or rotavirus. But once she begins lactating, some of these same
antibody-producing cells suddenly begin taking a different "off-ramp," so to
speak, that leads to the mammary glands. That way, when her baby nurses, the
antibodies go straight to his intestine and offer protection while he builds
up his own immunity.

 

This is why previous studies have shown that formula-fed infants have twice
the incidence of diarrheal illness as breast-fed infants.

 

Until now, scientists did not know how the mother's body signaled the
antibody-producing cells to take the different off-ramp. The new study
identifies the molecule that gives them the green light.

 

"Everybody hears that breastfeeding is good for the baby," said Eric Wilson,
the Brigham Young University microbiologist who is the lead author on the
study. "But why is it good? One of the reasons is that mothers' milk carries
protective antibodies which shield the newborn from infection, and this
study demonstrates the molecular mechanisms used by the mother's body to get
these antibody-producing cells where they need to be."

 

Understanding the role of the molecule, called CCR10, also has implications
for potential future efforts to help mothers better protect their infants.

 

"This tells us that this molecule is extremely important, so if we want to
design a vaccine for the mother so she could effectively pass protective
antibodies to the child, it would be absolutely essential to induce high
levels of CCR10," said Wilson.

 

Speaking broadly about the long-term applications of this research, BYU
undergraduate Elizabeth Nielsen Low, a co-author on the paper, said, "If we
know how these cells migrate, we'll be able to hit the right targets to get
them to go where we want them."

 

Daniel Campbell is a researcher at the Benroya Research Institute in
Seattle, a nonprofit organization that specializes in the immune system, and
was not affiliated with this study.

 

"The molecular basis for this redistribution [of the mother's cells] has not
been well characterized, but Dr. Wilson's work has begun to crack that code
and define the molecules responsible for this cellular redistribution and
passive immunity," Campbell said. "It is important work that fundamentally
enhances our understanding of how immunity is provided to the [baby] via the
milk. Dr. Wilson's study will certainly form the basis for many other
studies aimed at uncovering how the immune system is organized, particularly
at mucosal surfaces."

 

To conduct their research, the team used so-called "knock-out mice" that had
been genetically engineered to lack the CCR10 molecule. Whereas normal
lactating mice had hundreds of thousands of antibody-producing cells in
their mammary glands, the BYU team found that the knock-out mice had more
than 70 times fewer such cells. Tests verified that the absence of CCR10 was
responsible for the deficiency.

 

Surprisingly, the research also showed that CCR10 does not play the same
crucial role in signaling antibody-producing cells to migrate to the
intestine. Another molecule is their "traffic light."

 

The findings will be published in the Nov. 1 issue of the Journal of
Immunology.

 

The study was supported by Wilson's grant from the National Institutes of
Health, funding which continues for another 18 months and supports his and
his students' further investigation into the cells behind transfer of
immunity in breast milk.

 

Wilson's other students who are also co-authors on the paper are Yuetching
Law, Kathryn Distelhorst and Erica D. Hill. The Harvard Medical School
co-authors are Olivier Morteau, Craig Gerard, Bao Lu, Sorina Ghiran and
Miriam Rits. The Stanford University School of Medicine co-authors are
Raymond Kwan, Nicole H. Lazarus and Eugene C. Butcher.

 

 

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Adapted from materials provided by Brigham Young University.

Brigham Young University (2008, October 27). How Breastfeeding Transfers
Immunity To Babies. ScienceDaily. Retrieved October 27, 2008, from
http://www.sciencedaily.com- /releases/2008/10/081026101713.htm


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