Changes in Human Milk Immunoglobulin Profile During Prolonged Lactation

Abstract

Mother's milk immunoglobulins (Igs) delivered to infants during breastfeeding are crucial in shaping and modulating immature infants' immune system and provide efficient protection against pathogens. The aim of the study was to evaluate the immunoglobulin concentrations in milk of 116 lactating mothers over prolonged lactation from the 1st to the 48th month using the ELISA method. The concentration of proteins, SIgA and IgG, but not IgM, showed a positive correlation (r = 0.69, p < 0.005; r = 0.54, p < 0.05; and r = 0.27, p < 0.05, respectively) with lactation from the 1st to the 48th month. The lowest concentrations of SIgA and IgG were observed for the first year (2.12 ± 0.62 g/L and 14.71 ± 6.18 mg/L, respectively) and the highest after the 2nd year of lactation (7.55 ± 7.16 g/L and 18.95 ± 6.76 mg/L, respectively). The IgM concentration remained stable during 2 years (2.81 ± 2.74 mg/L), but after 24 months it was higher (3.82 ± 3.05 mg/L), although not significantly. Moreover, negative correlations of protein (r = −0.24, p < 0.05) and SIgA (r = −0.47, p < 0.05) concentrations with the number of feedings were found. Human milk after the 2nd year of lactation contains significantly higher concentrations of protein, SIgA, and IgG. High concentration of immunoglobulins and protein during prolonged lactation is an additional argument to support breastfeeding even after introducing solid foods and should be one of the overarching goals in the protection of children's health.

Detection of breastmilk antibodies targeting SARS-CoV-2 nucleocapsid, spike and receptor-binding-domain antigens

“…Conversely, we found higher levels of anti-SARS-CoV2 antibodies in the breast milk, when compared to serum. This is in line with secretory IgA being the most abundant Ig in human milk, representing more than 90% of the total breast milk Ig [ 2 ].

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Lactoferrin and Immunoglobulin Concentrations in Milk of Gestational Diabetic Mothers

“…Breastfeeding is known to play an essential role in nutrition programming in the early stages of growth and have an impact on lowering the risk of developing diabetes and obesity in later life [ 87 ]. Maturation of maternal milk is related to dynamic changes in both nutritional and bioactive components, including immunologically important molecules such as innate and adaptive factors [ 38 , 40 , 59 , 76 ]. From the first to fifteenth day of lactation, the concentrations of LF and SIgA were negatively correlated with milk maturation of hyperglycemic ( r = −0.37 and r = −0.48, respectively) and normoglycemic mothers ( r = −0.31 and r = −0.48, respectively), and the values of coefficients were at almost the same level.…”

“…The concentrations of all analyzed immunoglobulins—SIgA, IgG, and IgM—in defatted milk samples were quantified by the enzyme-linked immunosorbent assay (ELISA) previously developed with slight modification [ 40 , 76 , 84 ]. In short, for all determinations, microtiter plates (Nunc International, Naperville, IL, USA) were used.…”

“…Feeding maternal milk is considered as a gold standard of early postnatal nutrition and provides a valuable source of a wide range of innate and adaptive components and bioactive molecules for term and preterm newborns [ 34 , 35 , 36 ]. The major immune components delivered with maternal milk are lactoferrin (LF) and secretory immunoglobulin A (SIgA) [ 37 , 38 , 39 , 40 ]. Both molecules effectively support the immature newborn’s immune system and protect against colonization of gastrointestinal and respiratory tracts by pathogens, reducing the incidence of respiratory infections, sepsis, necrotizing enterocolitis, and diarrhea [ 41 , 42 , 43 , 44 , 45 , 46 , 47 ].…”

“…Nevertheless, the specificity of transferred immunoglobulins is limited to the range of pathogens with which the mother’s immune system has come into contact earlier [ 64 , 65 ]. Although the concentrations of immunoglobulin G and M (IgG and IgM) in maternal milk are significantly lower, both support the protective and modulatory actions of SIgA [ 40 , 66 , 67 ]. Taken together, the maternal milk-delivered fraction of immunoglobulins provides passive immunity to the infant [ 49 ] and is one of the crucial factors by which lactating mothers can protect breastfed newborns from a wide range of pathogens [ 46 ].…”