The Effect of Breast Feeding on Lymphocyte Subpopulations in Healthy Term Infants at 6 Months of Age

Abstract

Breast milk contains many immunologically active components that influence the development of the immune system of the breast-fed infant. The purpose of this study was to investigate the difference in specific lymphocyte subsets between breast-fed and formula-fed 6-mo-old infants. Peripheral blood samples were collected from 79 breast-fed (< 120 mL formula/wk) and 69 formula-fed (breast-fed < 4 wk) infants at 6 mo. All infants had been born at term and had no known illness at the time of blood collection. Packed cells from whole blood were incubated with fluorochrome-labeled monoclonal antibodies, followed by erythrocyte lysis. Washed lymphocytes were analyzed by two-color direct immunofluorescence on a flow cytometer. The percentage of T and B lymphocytes in the peripheral blood of 6-mo-old infants was the same, regardless of feeding regimen. However, the relative frequency of natural killer (NK) cells was greater in breast-fed infants than in formula-fed infants (9.7% vs 7.1%; p < 0.001). The percentage of cells expressing CD4 was lower in breast-fed infants than in formula-fed infants (47.3% vs 50.9%; p < 0.005), and that of cells expressing CD8 was greater (18.0% vs 16.4%; p < 0.05). As a result, the CD4:CD8 ratio in breast-fed infants was lower than that in formula-fed infants (2.8 vs 3.3; p < 0.005). The absolute size of the lymphocyte subpopulations T, B, and CD8+ was the same for each of the two populations of infants. However, breast-fed infants had fewer CD4+ T cells (p < 0.05) and a greater number of NK cells (p < 0.01) than the age-matched formula-fed infants. The immunophenotypic differences between breast-fed and formula-fed infants are consistent with reported age-related changes, suggesting greater maturity in the development of the immune system of breast-fed infants.

Protective effect of breastfeeding against childhood leukemia in Zhejiang Province, P. R. China: a retrospective case-control study

“…A great number of natural-killer cells, suggesting a more mature immune system, have been found in breastfed infants than in formula-fed infants [27]. In addition, the pH level (hydrogen ion concentration, which can activate pepsin and promote protein digestion and absorption) in the stomach of breastfed children is better for the promotion of the protein-lipid α-lactalbumin, which induces apoptosis like death of tumor cells [28,29]. Infant formulas cannot mimic the array of protective properties of breast milk, which fits the infant owing to the dyadic connection between a mother and her baby.…”

Early nutrition and the development of immune function in the neonate

“…However, some recent studies have shown that immunophenotypic differences in lymphocyte populations occur following exposure to maternal milk. These differences include a decrease in CD4+:CD8+ cells, an increase in interferon-γ levels and a greater number of natural killer cells (Pabst et al 1997;Hawkes et al 1999), and are consistent with age-related changes, suggesting that maternal milk can influence the maturation of the neonatal immune system (Hawkes et al 1999). The mechanism whereby maternal milk may induce these effects is not known.…”

Nitrate and Nitrite Content of Human, Formula, Bovine, and Soy Milks: Implications for Dietary Nitrite and Nitrate Recommendations

“…Infants who are breastfed exclusively for 6 months have a more developed immune system than those who are not exclusively breastfed. 40,41 Breastfeeding has also been shown to reduce the risks of the infant developing asthma and allergies 42 as well as childhood leukemia. 43 Cardiovascular disease risk is also reduced through the reduction of obesity, blood pressure, and cholesterol.…”