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




How Breastfeeding Transfers Immunity To Babies  

							

				ScienceDaily (Oct. 27, 2008)
—
 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.
				
				
				
				
				
				Adapted from materials provided by Brigham Young University.
				
				
					
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							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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