Daily Ingestion of Immunologic Components in Human Milk during the. First Four Months of Life

ABSTRACT. The amounts of lactoferrin, lysozyme, SIgA and SIgA antibodies to E. coli somatic antigens in human milk ingested per day and per kg per day by breast-fed infants were determined during the first four months of life. A gradual decline in the amounts of lactoferrin, SIgA, and SIgA antibodies ingested per day or per kg per day was found, whereas the quantities of lysozyme ingested by the infants rose during that period. These data suggest that the production and secretion of these immunologic factors by the mammary gland may be linked to the ontogeny of the production or catabolism of those components at mucosal tissues of the recipient infant.     

Enhanced fecal excretion of selected immune factors in very low birth weight infants fed fortified human milk

The amounts of lactoferrin, lysozyme, total IgA, secretory IgA (SIgA), and specific SIgA antibodies to a pool of Escherichia coli O antigens were measured in 96-h collections of feces obtained from 28 very low birth weight infants, 28-30 wk of gestation, studied at 2.5 and 6 wk of age. Eighteen of these infants were fed their mothers' milk fortified with fractions of skim and cream derived from pasteurized, lyophilized, mature human milk (FM) and 10 infants were fed commercial cow's milk-based formula. The concentrations of these selected immune factors in the FM and formula also were measured. Specific SIgA antibodies to E. coli O antigens were detected in the feces of 90% of the FM-fed infants, but in none of the feces of the formula-fed infants. The feces obtained from FM-fed infants had markedly greater quantities of lactoferrin (p less than 0.001), lysozyme (p = 0.006), and IgA (p less than 0.001) than those of cow's milk formula-fed infants. The concentrations of total and secretory IgA were correlated significantly (r = 0.88, p less than 0.001) and 95% of total IgA was SIgA. The fecal concentration of specific SIgA antibodies to E. coli O antigens in FM-fed infants correlated with the concentration of these antibodies in their milk (p less than 0.001). However, there were no direct relationships between the milk concentrations or the infant's intakes of the other selected immune factors and the excretion of these factors in the feces.(ABSTRACT TRUNCATED AT 250 WORDS)     

Human milk feeding enhances the urinary excretion of immunologic factors in low birth weight infants

The effects of fortified human milk feedings on the urinary excretion of lactoferrin, lysozyme, secretory component, IgA, and secretory IgA antibodies to Escherichia coli O antigens were investigated in very low birth wt infants. Infants were maintained on either a human milk or a cow's milk preparation. The amounts of each immune factor that were ingested and excreted were quantified during balance studies conducted at 2.5 and 5 wk of age. Serum levels of these immune factors were similar in both feeding groups. The urinary excretion of all factors except lysozyme was 7- to 150-fold greater in infants fed human milk than in those fed cow's milk formula. IgA was the only factor for which the amount of the factor excreted correlated with the amount ingested. Fragments as well as whole molecules of lactoferrin were found in the urine of the infants fed human milk, but the molecular sizes of the excreted proteins exceeded those normally filtered by the kidneys. Therefore, the genesis of the enhanced levels of host defense factors in the urine of infants fed human milk is not clear. Gastrointestinal absorption and subsequent renal excretion as well as enhanced production of immune factors in the infant's urinary tract are possible explanations.     

Quantity and quality of milk protein intake: metabolic responses in the neonate

All whey proteins in human milk are not absorbed and thus not nutritionally available. There is evidence that SIgA, lactoferrin and lysozyme are resistant to proteolytic action and the major part of these protective proteins are excreted in the infants stool. An exclusively breast-fed infant would thus have a mean intake of 1.3 g of protein per kg/d during the first month and about 0.9 g/kg/d during the third month. Term infants fed with formulas containing 1.5 g of protein per 100 ml show metabolic changes which indicate that they receive more protein than they require for growth, these changes are not seen in breast-fed infants or in infants receiving a whey-predominant formula containing only 1.1 g/100 ml of protein. A reevaluation of protein requirement and intake during infancy is suggested.     

Breast feeding: Overview and breast milk immunology

The transfer of host defence capacity to the human offspring provides a remarkable model of passive transfer of immunity. In fact it may also provide an example of active immunization. The transfer of mucosal protection via breast feeding offers many additional advantages for the mother and infant. Through its contraceptive effects it increases the spacing between births, thus diminishing the infant mortality and the burden on the mother. It also enhances bonding between mother and child, it seems to increase the IQ and school result of the infant and might decrease the risk of certain malignancies and perhaps of juvenile diabetes. A fully breast-fed infant receives as much as 0.5-1 g of secretory immunoglobulin A (SIgA) antibodies daily, the predominant antibody of human milk. This can be compared to the production of some 2.5 g of SIgA per day for a 60 kg adult. These SIgA antibodies have been shown to protect against Vibrio cholerae, ETEC, Campylobacter, Shigella and Giardia. Furthermore, milk is rich in receptor analogues for certain epithelial structures which microbes need for attachment to host tissues as an initial step in infections. Thus the adherence of Haemophilus influenzae and pneumococci for example to retropharyngeal cells is efficiently inhibited by human milk. This may be one explanation for the fact that breast-fed babies have less otitis media than the non-breast-fed. Other milk factors like lysozyme and lactoferin may contribute to the host defence, but this has not yet been well defined. However, human milk also supports the well-being of the infant by being anti-inflammatory. The predominant SIgA antibodies and the receptor analogues prevent microbes from getting into contact with host tissues causing tissue inflammation via inflammatogenic immunoglobulin G and immunoglobulin M antibodies and activated T lymphocytes. Rather, milk proteins like lactoferrin can inhibit the production of inflammatogenic cytokines like interleukin-6 from intestinal epithelium and monocytes/macrophages. Breast feeding enhances vaccine responses in the infant. This may occur via immunostimulation effects via anti-antibodies present in the milk. Human milk truly provides an unequalled mixture of factors supportive of the health of the infants. Many factors may still remain to be discovered.     

THE MUCOSAL IMMUNE RESPONSE IN THE NEONATE

Hanson LÅ, Brinton C, Carlsson B, Dahlgren U, Mellander L, Sutton A and Söderström T. (Departments of Clinical Immunology and Paediatrics, University of Göteborg, Sweden, Bureau of Biologies, FDA, Bethesda, and Department of Life Sciences, University of Pittsburg, USA). The mucosal immune response in the neonate. Acta Paediatr Scand, Suppl. 296:53, 1982. — Human infants are relatively deficient in the IgA system defending mucosal membranes, but are provided via the maternal milk with considerable amounts of SIgA directed against microbes and food antigens to which both mother and infant are exposed. It is possible that serum antibodies may support the mucosal defense as do the lactoferrin, lysozyme and other defense factors present in the milk.     

Salivary anti-RSV IgA antibodies and respiratory infections during the first year of life in atopic and non-atopic infants

Salivary SIgA antibodies against RS virus were studied in 105 children during the first year of life. The infants were divided into groups according to their risk of atopy. At birth 13 neonates showed measurable amounts of SIgA to RS virus. In another 26 children specific antibodies were detected but in concentrations too low for quantitative analysis. During the first year of life this increased to 29 antibody-positive samples with measurable amounts of antibody and 39 with concentrations too low for quantitative determination. At this time 8 children of the high risk group had developed symptoms of allergy. None of these children had measurable amounts of SIgA anti-RSV in their saliva. In comparison, 10 of the remaining 26 high risk infants without symptoms of allergy did have such antibodies. Atopic infants had significantly more respiratory infections during the first year of life than nonatopic infants. The avidity of SIgA anti-RSV in neonatal samples was significantly higher than avidity determined in breast milk SIgA but comparable to the avidity of serum IgG. During the first year of life a continuing decrease of salivary SIgA avidity was observed.     

Persistence of human milk proteins in the breast-fed infant

Several proteins in human milk are postulated to have physiological functions in the breast-fed infant. Therefore, survival of human milk proteins after passage through the gastrointestinal tract of the breast-fed infant was investigated. Fecal samples were collected from exclusively breast-fed term infants and milk samples from their mothers. Soluble proteins in the feces were extracted and analyzed for total protein, nitrogen, lactoferrin, secretory IgA, serum albumin and lysozyme. Significant amounts of lactoferrin and secretory IgA were excreted by the infants and this excretion decreased throughout the study period in a trend similar to the decreasing milk concentrations of these proteins. Gel filtration demonstrated excreted lactoferrin and secretory IgA to be intact. No serum albumin or lysozyme was detected in the fecal extracts. Crossed immunoelectrophoresis showed three human milk proteins to be present in the feces--the third was identified as alpha 1-antitrypsin. Excretion of these proteins indicates the total protein content of human milk is an over-estimation of the protein nutritionally available to the infant.     

Breast-milk Antimicrobial Factors of Rural Gambian Mothers: Influence of Stage of Lactation and Maternal Plane of Nutrition

ABSTRACT. The concentrations of IgA, IgG, IgM, C3, C4, lactoferrin, lysozyme and secretory component in the mature breast milk of 152 rural Gambian mothers were measured up to 26 months lactation. The concentrations and daily secretion of all the immunoproteins, except lysozyme, decreased during the first year of lactation, but were well maintained thereafter. The production of lysozyme increased progressively throughout lactation. Compared with 10 mothers in Cambridge, U.K., the daily secretion of IgG, IgM, C3 and C4 was higher in The Gambia, that of IgA and lactoferrin was similar in the two communities, and that of lysozyme and secretory component was lower in The Gambia. A dietary supplement given to 90 Gambian mothers, raised the mean daily energy intake from a maximum of 1650 kcal/day and a hungry-season minimum of 1200 kcal/day to 2300 kcal/day throughout the study. The supplement did not enhance the production of breast milk immunoproteins.     

Breast-milk antimicrobial factors of rural Gambian mothers. I. Influence of stage of lactation and maternal plane of nutrition

The concentrations of IgA, IgG, IgM, C3, C4, lactoferrin, lysozyme and secretory component in the mature breast milk of 152 rural Gambian mothers were measured up to 26 months lactation. The concentrations and daily secretion of all the immunoproteins, except lysozyme, decreased during the first year of lactation, but were well maintained thereafter. The production of lysozyme increased progressively throughout lactation. Compared with 10 mothers in Cambridge, U.K., the daily secretion of IgG, IgM, C3 and C4 was higher in The Gambia, that of IgA and lactoferrin was similar in the two communities, and that of lysozyme and secretory component was lower in The Gambia. A dietary supplement given to 90 Gambian mothers, raised the mean daily energy intake from a maximum of 1650 kcal/day and a hungry-season minimum of 1 200 kcal/day to 2 300 kcal/day throughout the study. The supplement did not enhance the production of breast milk immunoproteins.     

Supplementation of an adapted formula with bovine lactoferrin. 2. Effects on serum iron, ferritin and zinc levels

Breast milk provides an excellent supply of most nutrients for newborn infants. Infant formulae should be nutritionally comparable to breast milk especially with regard to critical nutrients like iron and other trace elements. Infant formulae supplemented with various amounts of bovine lactoferrin were given to two groups of infants. These infants were compared with infants receiving unsupplemented formula and breast-fed infants. The effects of these diets on levels of haemoglobin, haematocrit, serum iron, ferritin and zinc were examined for a study period of 150 days. At birth, concentrations of iron, haemoglobin, haematocrit and zinc were comparable in all four feeding groups. The fact that the serum zinc level was not altered by lactoferrin supplementation appears to rule out an in-vivo effect of lactoferrin on zinc nutrition of infants. Ferritin levels of breast-fed infants were significantly higher than in non-supplemented formula-fed infants at day 30 and day 90. This difference was seen only at day 30, when comparing breast-fed infants to lactoferrin-supplemented formula-fed infants. Comparing the infants receiving formulae, the formula supplemented with the higher amount of bovine lactoferrin induced significantly higher serum ferritin levels compared to the unsupplemented formula at day 90 and day 150. These observations favour the idea that lactoferrin may be involved in iron absorption. Since this effect was pronounced only after 90 days, it has to be discussed as to whether this effect is a convincing argument for supplementing infant formulae with bovine lactoferrin.     

Cytokine, chemokine and secretory IgA levels in human milk in relation to atopic disease and IgA production in infants

The relationship between breast-feeding, IgA production and development of atopic disease in children is a matter of controversy. Some of this controversy might be due to individual differences in the composition of breast milk. The aim of this study was to relate the levels of cytokines, chemokines and secretory (S)-IgA antibodies in breast milk to the development of atopic manifestation and salivary IgA production in infants. Cytokine, chemokine and SIgA levels, as measured with enzyme-linked immunosorbent assay (ELISA), in colostrum and mature milk were analyzed in relation to the development of positive skin-prick tests (SPT), allergic symptoms and salivary IgA antibody production during the first 2 years of life in 53 infants. There was no association between levels of IL-4, -5, -6, -8, -10, -13, -16, IFN-γ, TGF-β1, -β2, RANTES, eotaxin or SIgA levels in the breast milk with either SPT-positivity, development of allergic symptoms or salivary IgA levels during the first 2 years of life in the infants. Thus, differences in the composition of cytokines, chemokines and SIgA in breast milk did not, to any major degree, affect the development of a positive SPT, atopic symptoms, nor salivary IgA antibody production during the first 2 years of life.     

Persistence of Human Milk Proteins in the Breast-Fed Infant

Several proteins in human milk are postulated to have physiological functions in the breastfed infant. Therefore, survival of human milk proteins after passage through the gastrointestinal tract of the breast-fed infant was investigated. Fecal samples were collected from exclusively breast-fed term infants and milk samples from their mothers. Soluble proteins in the feces were extracted and analyzed for total protein, nitrogen, lactoferrin, secretory IgA, serum albumin and lysozyme. Significant amounts of lactoferrin and secretory IgA were excreted by the infants and this excretion decreased throughout the study period in a trend similar to the decreasing milk concentrations of these proteins. Gel filtration demonstrated excreted lactoferrin and secretory IgA to be intact. No serum albumin or lysozyme was detected in the fecal extracts. Crossed Immunoelectrophoresis showed three human milk proteins to be present in the feces—the third was identified as α₁-antitrypsin. Excretion of these proteins indicates the total protein content of human milk is an over-estimation of the protein nutritionally available to the infant.     

Iron availability from an infant formula supplemented with bovine lactoferrin

Iron balance studies were performed in 16 term infants from their 3rd until their 17th week of life. The balance studies were performed at home and comprised five periods with an interval of 3 to 4 weeks, each consisting of three 24-hour collections of milk and stool samples. Seven infants were fed an adapted infant formula supplemented with bovine lactoferrin (100 mg/100 ml) and nine received the same formula without lactoferrin. The lactoferrin supplemented group received 169 micrograms iron/kg b.w. x day and retained 63 micrograms/kg b.w. x day. The mean iron intake of infants fed with the adapted formula without supplementation of lactoferrin was 118 micrograms/kg b.w. x day. The retention of iron was 43 micrograms/kg b.w. x day. Mean percentage retention of iron in the supplemented group was 36%, in the non-supplemented group 28%.     

Iron Availability from an Infant Formula Supplemented with Bovine Lactoferrin

ABSTRACT. Iron balance studies were performed in 16 term infants from their 3rd until their 17th week of life. The balance studies were performed at home and comprised five periods with an interval of 3 to 4 weeks, each consisting of three 24-hour collections of milk and stool samples. Seven infants were fed an adapted infant formula supplemented with bovine lactoferrin (100 mg/100 ml) and nine received the same formula without lactoferrin. The lactoferrin supplemented group received 169 μg iron/kg b.w. × day and retained 63 μg/kg b.w. × day. The mean iron intake of infants fed with the adapted formula without supplementation of lactoferrin was 118 μg/kg b.w. × day. The retention of iron was 43 μg/kg b.w. × day. Mean percentage retention of iron in the supplemented group was 36%, in the non-supplemented group 28%.     

Faecal SIgA secretion in infants fed on pre- or probiotic infant formula

Secretory immunoglobulin A (SIgA) plays an important role in the defence of the gastrointestinal tract. The level of faecal SIgA antibody is associated with increased neutralization and clearance of viruses. Formula-fed infants who lack the transfer of protective maternal SIgA from breast milk may benefit from strategies to support maturation of humoral immunity and endogenous production of SIgA. We aimed at studying the effects of standard, prebiotic and probiotic infant formulas on the faecal SIgA levels. At birth, infants of whom the mother had decided not to breastfeed were allocated to one of three formula groups in a randomized, double-blind fashion. Nineteen infants received standard infant formula; 19 received prebiotic formula containing a specific mixture of 0.6 g galacto-oligosaccharides (GOS)/fructo-oligosaccharides (FOS)/100 ml formula and 19 received probiotic formula containing 6.0 × 10⁹ cfu Bifidobacterium animalis /100 ml formula. Faecal samples were taken on postnatal day 5, day 10, wk 4 and every 4 wk thereafter until wk 32. SIgA in faeces was determined by an enzyme-linked immunosorbent assay. During the intervention, infants fed on prebiotic formula showed a trend towards higher faecal SIgA levels compared with the standard formula-fed infants reaching statistical significance at the age of 16 wk. In contrast, infants fed on the probiotic formula showed a highly variable faecal SIgA concentration with no statistically significant differences compared with the standard formula group. Formula-fed infants may benefit from infant formulas containing a prebiotic mixture of GOS and FOS because of the observed clear tendency to increase faecal SIgA secretion. Adding viable B. animalis strain Bb-12 to infant formula did not reveal any sign for such a trend.     

Local antibodies to alpha-casein and beta-lactoglobulin in the saliva of infants

Salivary antibodies were studied in 112 infants between 1 day and 8 yr of life. SIgA anticasein was present from birth in breast-fed and bottle-fed infants. Bottle-feeding resulted in significantly higher concentrations of SIgA anticasein at 3 wk to 3 months of life as compared to breast-feeding. Salivary anticasein declined toward the end of the 1st yr and was present in less than half of the children older than 1 yr. Salivary anti-beta-lactoglobulin was also present at birth in some infants. Levels increased slightly over the following 3 months but remained low. Only a minority of older children had this antibody in their saliva.     

Lactoferrin and lysozyme deficiency in airway secretions: association with the development of bronchopulmonary dysplasia.

To test whether the presence of airway inflammatory markers differentiated babies with hyaline membrane disease (HMD) who recovered (n = 18) from those in whom bronchopulmonary dysplasia (BPD) developed (n = 18), tracheal aspirate samples from 36 newborn infants with HMD who underwent intubation were collected during days 1 to 28 of life and analyzed for the mucosal antimicrobial proteins lactoferrin and lysozyme. For babies with HMD in whom BPD developed, lactoferrin concentrations were decreased during the first 4 days of life (7 +/- 3, 14 +/- 3, 18 +/- 3, and 18 +/- 3 micrograms/ml, respectively) in comparison with those in babies with HMD who recovered (23 +/- 8, 29 +/- 6, 41 +/- 9, and 81 +/- 19 micrograms/ml); group differences reached statistical significance on days 3 and 4 (p less than 0.05). Lysozyme levels in the secretions of babies with BPD were also lower on day 3 (31 +/- 5 micrograms/ml) than in those of babies who recovered (54 +/- 7.5 micrograms/ml). For babies with BPD whose endotracheal tube remained in place beyond day 4, lysozyme levels on days 5 to 12 were significantly lower for those classified as having severe BPD than for those with mild to moderate BPD. Because lysozyme and lactoferrin are products of serous cells found in submucous glands, it seems possible that the relative immaturity of submucous glands may influence the development of BPD.     

High salivary secretory IgA antibody levels are associated with less late‐onset wheezing in IgE‐sensitized infants

To cite this article: Sandin A, Björkstén B, Böttcher MF, Englund E, Jenmalm MC, Bråbäck L. High salivary secretory IgA antibody levels are associated with less late‐onset wheezing in IgE‐sensitized infants. Pediatr Allergy Immunol 2011; 22 : 477–481. Low levels of secretory IgA (SIgA) and transient IgA deficiency have been associated with an increased risk for allergy, but data are conflicting. The aim was to assess the relationship between salivary SIgA antibody levels at 1 yr and wheezing at age four in a birth cohort, in particular the possible protective role of salivary SIgA in sensitized children. Saliva samples were obtained from all children (n = 67) with a positive skin prick test (SPT) at 1 yr and 212 children with a negative SPT. In all, 200 of these children responded to questionnaires at 4 yrs and 183 were skin prick tested at that age. The levels of salivary SIgA and salivary IgA antibodies to the most common food allergen egg and inhalant allergen cat were analyzed by ELISA. Serum was analyzed for IgE antibodies to egg and cat. Development of late‐onset wheezing was associated with low SIgA levels in children with positive SPT to at least one allergen both at 1 and 4 yrs of age (p = 0.04), as well as in children with circulating IgE antibodies to egg or cat at 1 yr (p = 0.02). None of nine persistently sensitized children with SIgA levels in the upper quartile developed wheezing, when compared to 10/20 children with lower levels (p = 0.01). Older siblings, more than three infections during infancy, at least one smoking parent, and male gender, were all associated with SIgA in the upper quartile. In conclusion, high levels of SIgA antibodies in sensitized infants were associated with significantly less late‐onset wheezing, supporting a protective role against development of asthmatic symptoms. Recurrent infections and other factors supporting an increased microbial pressure during infancy were associated with high levels of salivary SIgA.     

Fecal secretory immunoglobulin A in breast milk versus formula feeding in early infancy

We studied the effects of breast milk feeding versus formula feeding during the first 8 weeks of life on the development of local gastrointestinal humoral immune response by measuring fecal secretory immunoglobulin A (SIgA). Forty-four infants were studied and classified into two groups: breast milk (n = 21) and standard Enfamil without iron (n = 23). The fecal specimens were analyzed at birth and 2, 4, and 8 weeks of age. Radial immune diffusion (RID) technique was used to assay the fecal SIgA during these four ages. Marked SIgA changes were detected in the breast milk-fed group. At birth, no fecal SIgA was detected in either group. At 2, 4, and 8 weeks, significant differences were found between the two groups (p4 less than or equal to 0.001 and p8 less than or equal to 0.001). This phenomenon of enhanced fecal SIgA in breast-fed infants versus standard formula-fed infants is not caused solely by the presence of IgA in breast milk; it represents a stimulatory effect of breast milk on the gastrointestinal humoral immunologic development. The possible active stimulatory role of breast milk on the development of immunologic competence and host defense is discussed. These data suggest an additional advantage of breast milk feeding during early life by the protective role of the earlier and enhanced production of SIgA in the gastrointestinal tract.