1.2 Immunology
At birth, the baby's skin and gut is sterile, but is quickly colonized by the bacterial flora of those with whom he comes in contact.

Clinical Tip:
A simple strategy to ensure the baby's skin is colonized by the flora common to his mother is to limit the handling of the newborn by health care workers until after the mother and baby have been together, in skin-to-skin contact, for a number of hours. Prolonged skin-to-skin contact also reduces the risk of the baby acquiring nosocomial infections.
Careful attention to hand hygiene is essential when it becomes necessary for staff members to handle the baby.
Soon after birth, the infant's gut is colonised by potentially harmful aerobic bacteria. The environment quickly changes as harmless anaerobic bacteria take over. Breastmilk supports this development of a protective anaerobic flora which may function as probiotics. Artificially-fed babies are colonized by aerobes and other anaerobes in addition to bifidobacteria, with a predominance of enterococci and enterobacteria. Clostridia, Enterococci, E. Coli and Bacteroides are also a common part of the gut flora of the artificially fed. 1
Protective components of breastmilk
Proteins
Immunoglobulins
Immunoglobulins are present in human milk. The special structure secretory IgA (sIgA) is the main immunoglobulin . Concentration in colostrum is particularly high to provide immediate protection for the infant entering a world of microbes.
- sIgA protection is 'targeted' against organisms with which the mother, and consequently her baby, come into contact, killing the offending pathogen
- sIgA coats the infant's intestine preventing adherence of pathogens, blocking them from getting onto and into the infant's tissues
- sIgA encourages the growth of the normal, non-virulent gut bacteria.
Lactoferrin
- has antibacterial (to gram-positive and gram-negative), antiviral and antifungal (Candida albicans) effects
- promotes the growth of intestinal epithelium
Alpha-Lactalbumin
- antiinfective and immunostimulatory functions
- forms a complex that induces apoptosis (= cell death) of all malignant cells tested, but not normal cells - known as HAMLET (human alpha-lactalbumin made lethal to tumour cells) 2
Lysozyme
- this enzyme effectively attacks E. coli in concert with lactoferrin and sIgA
Carbohydrates
Oligosaccharides
- prebiotic effect - produce an increased proliferation of bifidobacteria and lactobacilli (probiotics) which are not digested in the infant's small intestine, but enter the colon as intact, large carbohydrates that are then fermented by the resident bacteria.
- block receptors on epithelial surfaces by resembling binding sites for bacteria, sweeping the bacteria from the gut with them as they are eliminated
- defend infants against pathogens that cause otitis media, respiratory tract infections, urinary tract infections, diarrhoea.
Lipids and milk fat globules
Fatty acids and monoglycerides attack or neutralise G lamblia, Entamoeba, E coli, and Shiga-like toxins.
Cellular components
The neutrophils and macrophages in breastmilk most likely protect the maternal breasts.
Lymphocytes in breastmilk are absorbed and may possibly confer immunological information to the baby.
Other protective factors
Breastmilk contains a myriad of other factors that work to protect and enhance the development of the breastfed child, including nucleotides, defensins, cytokines, hormones and growth factors, anti-secretory factor, anti-inflammatory components, soluble CD14 and soluble Toll-like Receptor, etc.

Workbook Activity 1.4
Complete Activity 1.4 in your workbook.

Take a minute to reflect...
Breastmilk truly is a living food that is unique to each mother and baby. While artificial infant milk is life-saving for some babies, for the majority, it is an inferior source of food and protection.
What should I remember?

- Breastmilk is not just for nutrition
- There are many components which prevent and fight infections - know the main protective factors
- Artificial infant milk does not contain any immunological properties
Self-test Quiz
Match an item from the column on the left with an item from the column on the right. Click on an item in one column, then on its matching response from the other column