The following article was written by Sally Wendkos Olds, author (in consultation with Laura M. Marks, MD) of The Complete Book of Breastfeeding, 4th edition to be published in 2009 by Workman Publishing. I am most grateful to Sally for her willingness to share her expertise with the baby gooroo community!

By Sally Wendkos Olds

We have known for years that breastfed babies are protected from a great number of diseases. In developing countries, the survival rate for the breastfed baby may be six times greater than for his formula-fed cousin, and even among the children of middle- or upper-class parents in highly developed countries, breastfed babies are healthier and have better chances for survival. Breastfed babies make fewer visits to doctors’ offices and hospitals than formula-fed babies do, especially for diarrhea and other gastrointestinal disorders, rashes, and respiratory infections.

In technologically developed countries like the United States, where sanitary conditions are generally good, the gap in health between the breastfed and the formula-fed baby is narrowed considerably. In addition, modern medical techniques can now vanquish many of the illnesses that used to be fatal to infants. Still, it’s better to prevent disease than to cure it. And there’s a mountain of evidence that breast milk does indeed have preventive, protective powers.

But how breastfeeding babies get this protection has been a mystery until very recently. A research team from Brigham Young, Harvard, and Stanford universities has just published its findings in the Journal of Immunology to explain the mechanism responsible for at least some of this protection.

All of us have cells in our bodies that produce antibodies against intestinal infections. These cells circulate throughout our systems and regularly find their way to the intestine, ready to protect us against various illnesses we may be exposed to. When a woman has a baby and begins to produce milk, some of these same cells go to her mammary glands, which are located in the breasts. The antibodies produced by these cells then appear in her milk. Thus, when she breastfeeds her baby, these infection-fighting antibodies, now in her milk, go to her baby’s intestine and provide a temporary, passive immunity to various infections until he can develop his own immune system.

Eric Wilson, a Brigham Young University microbiologist and the lead author of the study, likens blood vessels to a freeway system.  “Travelers use the freeway system to get to desired locations,” he says, “and they know they’re at their destination by recognizing its address.” Dr. Wilson says that cells use the blood vessels much like a freeway, which lets them travel throughout the body, going to, say, the intestines from one freeway exit—or the mammary gland from another.

The researchers focused on identifying two aspects of this cellular freeway. An earlier study by Wilson and Butcher had identified two different molecules: The CCL25 molecule is the “address” for the mother’s intestines, and CCL28 is the “address” for her mammary gland tissue. The newly identified CCR10 molecule directs cells to the lactating mammary gland. To reach the mammary gland, the CCL28 and the CCR10 molecules bind together, and when the cell recognizes that CCL28 and CCR10 have bound, the cell leaves the blood, exiting into the mammary tissue, where it starts producing antibodies, which will then go into the milk.

The researchers compared mice that had been genetically manipulated to lack the CCR10 molecule and compared them to normal lactating mice, which had the molecule. They found that the mice without this molecule had more than 70 times fewer antibody-producing cells, showing that CCR10 is responsible for directing the crucial cells to the correct location.

This line of research may well lead to a vaccine that could improve a mother’s ability to pass a wide range of protective antibodies to her child by vaccinating her against different pathogens. Her immune system will learn to recognize each of these pathogens and produce antibodies to them; later when she’s exposed to these particular viruses or bacteria, the antibodies that her body has already produced in response to the vaccine will attack the disease organisms and eliminate them from her body before she gets infected. Meanwhile, she will have been able to pass these antibodies on to her breastfeeding baby to protect him against the same organisms.

This important work holds the promise of transforming the state of children’s health worldwide.

©  Sally Wendkos Olds