Every mother passes a unique set of antibodies to their babies through breast milk

A new study led by the University of Pittsburgh has found that breast milk from each mother contains a unique assemblage of antibodies that are surprisingly stable throughout lactation and across pregnancies.

Since a baby’s early immunity is strongly influenced by antibodies from breast milk, these findings shed new light on why protection against different infections varies among infants.

It also addresses why some of them develop a life-threatening gut disease called necrotizing enterocolitis (NEC). This awful disease is caused by bacteria from the family Enterobacteriaceae and mainly affects preterm and formula-fed infants.

“While each milk donor in our study had very different antibody profiles from one another, we found that antibodies from the same donor were quite similar over time — even across the span of months,” said senior author Timothy Hand. He is an associate professor of Pediatrics and Immunology at Pitt’s School of Medicine and UPMC Children’s Hospital of Pittsburgh.

“This means that if a baby’s parent happens to lack particular antibodies — such as those that fend off NEC, they’re never going to receive that immunity. This could help explain why some babies get NEC and others don’t.”

How antibodies in breast milk protects babies

Before their own immune system matures, babies are protected from harmful bacteria by antibodies transferred through their mother’s placenta and breast milk. These antibodies are highly efficient in binding to bacteria in the intestine and preventing them from invading the host.

In a previous study, Hand and his colleagues discovered that, while Enterobacteriaceae in fecal samples of healthy babies were mostly bound by maternal antibodies, babies who developed NEC had more bacteria that escaped being bound.

As the current study shows, this variation in infants’ immunity to NEC most likely happens because different mothers pass along different sets of antibodies.

The scientists analyzed donor breast milk from the Human Milk Science Institute & Biobank in Pittsburgh and Mommy’s Milk Human Milk Research Biorepository in San Diego. By exposing these samples to a variety of bacteria, they measured which strains each donor’s antibodies bound to.

“Individual donors’ antibody profiles looked completely different, which is what we had expected but were able to show for the first time,” Hand explained.

“During pregnancy, B cells travel from the intestine to the mammary gland, where they start making antibodies. The mom is trying to protect her infant using antibodies that she uses to protect her own intestine. Different women have led different lives, have different microbiomes and have encountered different infections, so it makes perfect sense that breast milk antibodies would reflect that variability.”

How the study was conducted

During the breastfeeding period, a mother’s milk changes from highly concentrated protein-rich colostrum into mature breast milk. Because of this, the experts also compared breast milk from the same donors over time. This allowed them to learn whether antibody composition also changes. Moreover, they examined milk samples from the same donors over multiple pregnancies.

“Not only were antibodies similar in donors across one pregnancy, they were also remarkably stable between infants. This suggests that when B cells arrive in the breast tissue, they don’t leave. This is important for understanding how babies acquire immunity and how they deal with infections,” Hand said.

Finally, since some B cells move to the mammary gland only during the third trimester, the scientists wanted to find out whether breast milk antibodies were different if a donor delivered preterm. Fortunately, the analysis revealed that those who delivered preterm had just as many antibodies. They also had the same diversity as those who delivered full-term.

Although a mother’s own milk is best for reducing a premature baby’s risk of developing NEC, in cases when it is not available, donor milk could also work as a substitute or supplement.

However, since this milk is sterilized to kill bacteria, it will also contain fewer antibodies. Further research is needed to clarify what levels of antibodies are sufficient to provide protection against NEC and other diseases.

Better understanding which specific bacteria pose the most risks to preterm infants could help scientists develop antibodies which could be added to formula or breast milk to boost immunity.

More about breast milk and breastfeeding

Breast milk is a remarkable substance produced by the mammary glands in the human female body. It is designed to feed a newborn and infant child and is considered by many experts to be the optimal source of nutrition for infants. This is mainly due to its balance of nutrients and ability to boost the child’s immune system.

Here are some significant points regarding the importance of breast milk and breastfeeding:

Nutritional content

Breast milk contains the ideal mix of vitamins, protein, and fat for a baby’s growth and development. It’s more easily digestible compared to formula milk. It also contains antibodies that help your baby fight off viruses and bacteria.

Promotes immunity

Breast milk provides antibodies that help your baby fight off viruses and bacteria. Specifically, the first milk produced, called colostrum, is very rich in antibodies. Breastfeeding lowers your baby’s risk of having asthma or allergies.

Enhances brain development

There are significant positive effects of breast milk on a child’s brain development. Some studies suggest that children who were breastfed have higher IQ scores later in life, even when taking into account socio-economic factors.

Emotional and physical bonding

Breastfeeding creates a close bond between mother and baby due to the physical contact and nurturing. It also promotes a sense of security and warmth to the baby.

Beneficial for the mother

Breastfeeding not only benefits the baby but also the mother. It can help burn extra calories, which may help lose pregnancy weight faster. Breast milk also releases the hormone oxytocin, which helps the uterus return to its pre-pregnancy size and may reduce uterine bleeding after birth. It also reduces the risk of breast and ovarian cancer.

Breast milk is cost-Effective

Breastfeeding is cost-effective as it does not require the continual purchase of formula. This can provide significant savings for families.

Environmental impact

Breastfeeding has a lower carbon footprint compared to formula milk, which requires production, packaging, and transportation.

However, it’s essential to acknowledge that not all mothers can or choose to breastfeed due to various reasons, like medical issues, workplace conditions, personal choice, etc. In such cases, infant formula is a safe and viable alternative. It’s crucial to respect each individual’s decision and provide support as needed.

It’s also crucial to remember that babies’ nutritional needs change as they grow. The World Health Organization (WHO) recommends exclusive breastfeeding for the first six months of life.

At six months, solid foods, like mashed fruits and vegetables, should be introduced to complement breastfeeding for up to two years or more.

The study is published in the Journal of Experimental Medicine.

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By Andrei Ionescu, Earth.com Staff Writer

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