Antigenicity of infant formulas: role of immature intestine on protein permeability

Nutrition for full-term and preterm infants

Providing adequate nutrition for the healthy full-term newborn is relatively easy; breast milk or formula is sufficient for the first six months of life. Although the full-term infant's organ systems are relatively mature, the gastrointestinal tract is often stressed by the demands of rapid growth, and feeding difficulties, such as gastroesophageal reflux, colic, milk allergy, and constipation, may occur that necessitate special handling. The small preterm infant, however, has many urgent nutritional needs; management is usually complicated by the fact that the infant's immature organs may be unable to cope with enteral feedings. Thus, total parenteral nutrition is necessary, with extensive laboratory monitoring of metabolic functions and precise attention to detail to avoid a prolonged period of partial starvation.

A comprehensive review of sensitization and allergy to soy-based products

Since 1943, cases of sensitization or allergy to soy-based formulas (SBFs) have been described without any consensus on their real prevalence. We identified the adjusted prevalence of IgE-mediated soy allergies in children and performed a secondary analysis of the impact of age (less than and more than 6 months). We performed a systematic review with meta-analysis of studies published from 1909 to 2013 in PubMed, Embase, LILACS, ARTEMISA, Cochrane, Bandolier, DARE and the GRADE system for grading quality. Results are presented in tables and graphs using a forest plot. The 40 studies identified established weighted prevalence of soy allergies of 0 to 0.5 % (0.27) for the general population, 0.4 to 3.1 % (1.9) for the referred population, and 0 to 12.9 % (2.7) for allergic children. Prevalence of sensitization after the use of SBFs is 8.7 and 8.8 %, depending on the method used. The prevalence of allergies to soy and IgE sensitization to the use of SBFs is less than reported. Not enough evidence exists to show a higher risk of allergy in infants younger than 6 months. The concern about soy allergy is no reason to postpone the use of SBFs in IgE-mediated cow's milk allergy infants until the age of 6 months.

In vivo gut transcriptome responses to Lactobacillus rhamnosus GG and Lactobacillus acidophilus in neonatal gnotobiotic piglets

Probiotics facilitate mucosal repair and maintain gut homeostasis. They are often used in adjunct with rehydration or antibiotic therapy in enteric infections. Lactobacillus spp have been tested in infants for the prevention or treatment of various enteric conditions. However, to aid in rational strain selection for specific treatments, comprehensive studies are required to delineate and compare the specific molecules and pathways involved in a less complex but biologically relevant model (gnotobiotic pigs). Here we elucidated Lactobacillus rhamnosus (LGG) and L. acidophilus (LA) specific effects on gut transcriptome responses in a neonatal gnotobiotic (Gn) pig model to simulate responses in newly colonized infants. Whole genome microarray, followed by biological pathway reconstruction, was used to investigate the host-microbe interactions in duodenum and ileum at early (day 1) and later stages (day 7) of colonization. Both LA and LGG modulated common responses related to host metabolism, gut integrity, and immunity, as well as responses unique to each strain in Gn pigs. Our data indicated that probiotic establishment and beneficial effects in the host are guided by: (1) down-regulation or upregulation of immune function-related genes in the early and later stages of colonization, respectively, and (2) alternations in metabolism of small molecules (vitamins and/or minerals) and macromolecules (carbohydrates, proteins, and lipids). Pathways related to immune modulation and carbohydrate metabolism were more affected by LGG, whereas energy and lipid metabolism-related transcriptome responses were prominently modulated by LA. These findings imply that identification of probiotic strain-specific gut responses could facilitate the rational design of probiotic-based interventions to moderate specific enteric conditions.

The role of the gut mucosal immunity in the development of tolerance against allergy to food

PURPOSE OF REVIEW

To provide an overview on the role of gut mucosal immunity in the development of tolerance against allergy to food.

RECENT FINDINGS

The gastrointestinal tract, through innate and specific immunologic factors, acts as a defense against ingested antigens. In addition to the mucous membrane integrity and digestion, numerous specific immunologic cells and mediators orchestrate such defensive mechanisms. In case of food antigens, the outcome is usually in favor of tolerance. Defects in that barrier, however, can lead to the development of aberrant immunologic responses, including hypersensitivity reactions.

SUMMARY

The prevailing evidence is that healthy mucosal immunity plus appropriate feeding regimen during early infancy are in favor of food tolerance. However, in addition to genetic predisposition, development of allergy is facilitated by defects in the gut barrier (immune or nonimmune) and the food allergen load.

Allergic eosinophilic gastroenteritis with protein-losing enteropathy: intestinal pathology, clinical course, and long-term follow-up

OBJECTIVES

A subset of patients with allergic eosinophilic gastroenteritis (AEG) has anemia and hypoalbuminemia caused by protein-losing enteropathy (PLE). Our goals were to describe the response to therapy and the long-term outcome of patients in this subgroup and to evaluate their gastric and intestinal biopsies for distinguishing features that might explain their protein and blood loss.

METHODS

Patients with AEG + PLE were identified retrospectively and compared with controls and with patients with AEG only. Immunohistochemical staining for tryptase, a mast cell mediator, was performed on gastric and duodenal tissues. Eosinophils identified by hematoxylin/eosin stain and mast cells identified as tryptase-positive cells were counted in one high-power field area with maximal cell infiltration.

RESULTS

Although all patients had excellent response to therapy with amino acid-based formula and tolerated gradual introduction of some foods with time, food-responsive disease persisted in all patients over 2.5 to 5.5 years of follow-up. Routine histological evaluation did not show any features differentiating AEG + PLE from AEG. When eosinophils and mast cells were counted in intestinal biopsies, however, significantly more mast cells were found in biopsies of the AEG + PLE group despite comparable numbers of eosinophils. In contrast, in gastric biopsies, eosinophils were more prominent in AEG + PLE, but mast cell numbers were similar in all groups.

CONCLUSIONS

Patients with AEG + PLE responded well to therapy with amino acid-based formula. Food hypersensitivities did not completely resolve over up to 5.5 years. Intestinal mast cells were significantly increased in maximally infiltrated areas of the intestine, possibly causing increased intestinal permeability and protein loss.

Neonatal antibiotic treatment alters gastrointestinal tract developmental gene expression and intestinal barrier transcriptome

The postnatal maturation of the gut, partially modulated by bacterial colonization, ends up in the establishment of an efficient barrier to luminal antigens and bacteria. The use of broad-spectrum antibiotics in pediatric practices alters the gut bacterial colonization and, consequently, may impair the maturation of the gut barrier function. To test this hypothesis, suckling Sprague-Dawley rats received a daily intragastric gavage of antibiotic (Clamoxyl; an amoxicillin-based commercial preparation) or saline solution from postnatal day 7 (d7) until d17 or d21. Luminal microbiota composition and global gene expression profile were analyzed on samples from small intestine and colon of each group. The treatment with Clamoxyl resulted in the almost-complete eradication of Lactobacillus in the whole intestine and in a drastic reduction of colonic total aerobic and anaerobic bacteria, in particular Enterobacteriacae and Enterococcus. The global gene expression analysis revealed that Clamoxyl affects the maturation process of 249 and 149 Affymetrix probe sets in the proximal and distal small intestine, respectively, and 163 probe sets in the colon. The expression of genes coding for Paneth cell products (defensins, matrilysin, and phospholipase A2) was significantly downregulated by the Clamoxyl treatment. A significant downregulation of major histocompatibility complex (MHC) class Ib and II genes, involved in antigen presentation, was also observed. Conversely, mast cell proteases expression was upregulated. These results suggest that early treatment with a large-spectrum antibiotic deeply affects the gut barrier function at the suckling-weaning interface, a period during which the gut is challenged by an array of novel food-borne antigens.

Parental beliefs and practices regarding early introduction of solid foods to their children

This study was a cross-sectional survey of primary female caregivers during their child's 4-month well-child visit. Our objectives were to document current caregiver awareness of infant feeding guidelines, and calculate the frequency of and reasons for early introduction of solid foods. Questionnaires were completed for 102 children. Forty-five respondents (44%) introduced solids at less than 4 months of age. Hispanic caregivers, OR 0.2 (0.07-0.9), and those who breastfed (partial or exclusive), OR 0.4 (0.2-0.9), were less likely to introduce cereal at less than 4 months of age. Among caregivers who introduced solids at less than 4 months, 36 (80%) stated that the child was not satisfied with formula or breast milk alone and 24 (53%) stated that solids helped the child sleep better at night. Thirty-four caregivers (76%) who started solids at less than 4 months were aware of guidelines regarding proper infant feeding practices. Despite knowledge of infant feeding guidelines, female caregivers frequently introduce solids at less than 4 months of age. Early targeted anticipatory guidance is needed to address the most common reasons caregivers begin solid foods before the recommended age.

Xenobiotics and breastfeeding

Breastfeeding provides important benefits to mothers and infants and should be encouraged strongly as the optimal feeding choice for most infants. In assessing the effects of maternal medication on breastfeeding, clinicians must weigh the many benefits of breastfeeding for mothers and infants against the risk for exposing infants to a drug as it is present in breast milk. With regard to most medications, continued breastfeeding despite drug exposure is advantageous to mothers and infants.

Infant formula ingestion is associated with the development of diabetes in the BB/Wor rat

The association between early exposure to cow's milk products in infancy and risk for insulin dependent diabetes mellitus (IDDM) is controversial. We examined whether the ingestion of cow's milk-based infant formula altered the expression of the diabetic syndrome in the BB/Wor rat, an animal model of IDDM. Pregnant BB/Wor dams were obtained from the NIH contract colony at the University of Massachusetts and housed under semi-barrier conditions. Rat pups were intubated with 1 to 2 ml of commercially available cow's milk-based infant formula (Enfamil or Nutramigen) or sham intubated (controls) daily from day 12 to day 25 of life. Pups were weaned at day 25 and monitored for glucosuria daily through 120 days of life. All rats including dams consumed a milk-free rat chow and acidified water ad libitum throughout the study. The mean age of disease onset was 4 to 10 days earlier in Nutramigen-fed and Enfamil-fed rats relative to controls (84+/-3, 78+/-2 and 88+/-4 days, respectively); the mean age of disease onset was significantly different between controls and Enfamil-fed animals (p<0.05). At 120 days, 60% (12/20) of control rats developed diabetes versus 100% of animals fed either type of infant formula prior to weaning (15/15:Enfamil-fed; 19/19:Nutramigen-fed) (p<0.05). These data indicate that direct, early ingestion of cow's milk-based formula was related to the expression of diabetes in the BB/Wor rat.

Cow's milk enteropathy: surgical pitfalls

BACKGROUND

Cow's milk-induced intestinal bleeding is a well-recognized cause of rectal bleeding in infancy. The authors report on 5 older children who presented with either visible rectal bleeding or profound anemia associated with occult intestinal bleeding secondary to cow's milk enteropathy.

METHODS

Five children (3 boys and 2 girls) aged between 20 months and 9 years were referred for further investigation of gastrointestinal bleeding. Two had been investigated previously on multiple occasions, and both had undergone laparotomies with negative results. Further investigations showed evidence of allergic colitis in 3 detected only on proximal colonic biopsy findings.

RESULTS

In all cases, bleeding resolved completely after instituting a cow's milk-free diet. Two of the patients subsequently have undergone a cow's milk challenge leading to prompt recurrence of symptoms, which again resolved after simple dietary manipulation.

CONCLUSIONS

Cow's milk enteropathy may cause overt rectal bleeding or profound anemia from occult intestinal bleeding even in older children. Histological abnormalities in such cases may be confined to the proximal colon. After appropriate investigation, a trial of cow's milk exclusion should always be considered before laparotomy for obscure, chronic gastrointestinal bleeding in children.

Neither intact nor hydrolyzed soy proteins elicit intestinal inflammation in neonatal piglets

BACKGROUND

Efficacy of feeding hydrolyzed soy proteins to infants intolerant to cow milk proteins has not been determined fully. This study compared growth and intestinal responses of neonatal piglets fed formulas with hydrolyzed soy protein to piglets fed formulas with intact soy or cow milk (casein-whey) proteins.

METHODS

Piglets (n = 40, day 2 postpartum) were fed commercial milk replacer until day 7 postpartum (designated day 0) and then were assigned randomly to casein-whey (CW) or soy (intact, SI; hydrolyzed SH) formulas to evaluate intestinal responses on days 0, 2, 5, and 10.

RESULTS

Average daily gain was higher for CW (121 g/d; p < .05) compared with SI piglets 85 g/d); SH pig weight gain was intermediate (109 g/d). Villus height-to-crypt depth ratio in proximal jejunum was lower (p < .05) on day 2 than day 0 in soy-fed pigs and lower (p < .05) on day 5 than day 0 in CW pigs. Mucosal mast cells were generally higher in CW pigs compared with soy-fed pigs. Villus goblet cell numbers in the midjejunum of SH-fed piglets were lower (p < .05) on day 5 compared with day 0. On day 5, crypt goblet cell numbers were higher (p < .05) in the midjejunum of CW-fed piglets compared with SH-fed piglets with numbers intermediate for SI-fed piglets. Intestinal differences were not detected among dietary treatments for major histocompatibility complex class I and II gene expression, tissue concentrations of prostaglandin E2, or CD8+ T-cell numbers.

CONCLUSIONS

Hydrolyzed soy proteins do not elicit intestinal inflammatory responses in piglets and may be viable alternatives to milk and intact soy proteins for feeding infants.

Soy allergy is not common in atopic children: a multicenter study

The aim of the present study was to evaluate the prevalence of soy allergy (positive skin test and positive challenge test) in a large cohort of atopic children, many of them soy fed early in life for several months. In order to investigate the prevalence of soy allergy, two groups of children were enrolled into the study. The first group comprised a cohort of 505 children with personal history suggestive of food allergy. The second group included 243 children born of atopic parents, who had been soy protein formula fed for the first six months of life for the prevention of cow's milk allergy and who had been prospectively followed up, from birth to 5 years. As regards the prevalence of soy allergy in the cohort of children suffering from allergic disease: 31/505 children (6%) had positive skin prick test to soy, however only six of the 31 children with positive skin prick test to soy had positive challenge test to soy. With regard to the prevalence of soy allergy in the children who had been soy protein formula fed in the first six months of life (second group): 14/243 children (6%) had positive skin prick test to soy, but the double blind placebo control oral food challenge to soy was positive in only one of these 14 children. In conclusion documented soy allergy is not common in atopic children.

Prevention of food allergy

Development of a food allergy appears to depend on both genetic factors and exposure-especially in early infancy-to food proteins. In prospective studies, the effect of dietary allergy prevention programmes has only been demonstrated in high-risk infants, i.e. infants with at least one first degree relative with documented atopic disease. High-risk infants feeding exclusively on breast milk and/or extensively hydrolysed formula (eHF) combined with avoidance of cow's milk proteins and solid foods during at least the first 4 months of life are found to have a significant reduction in the cumulative incidence of food allergy, especially cow's milk protein allergy/intolerance (CMPA/CMPI), in the first 4 years of life. As no studies have been conducted pertaining to the preventive effect of avoidance of milk and other foods after the age of 4-6 months, recommendation of preventive elimination diets beyond this age is empirically based. In order to reduce costs and to minimize the risks of stigmatisation and malnutrition, it is important to avoid unnecessary restrictive and prolonged diets. A diet period of 4-6 months appears to be sufficient in the majority of infants. At present, eHF are recommended as a substitute for cow's milk. A few high risk infants may benefit from a maternal diet during lactation, but there is no documented beneficial effect of maternal dieting during pregnancy.

Dairy products and breast cancer: the IGF-I, estrogen, and bGH hypothesis

Research on the role of dietary factors in breast cancer causation has focused predominantly on fat intake. While some studies have examined associations between breast cancer rates and consumption of whole milk, there has been less attention given to dairy products in general. Dairy products contain both hormones and growth factors, in addition to fat and various chemical contaminants, that have been implicated in the proliferation of human breast cancer cells. This literature review evaluates the epidemiological and mechanistic evidence linking dairy consumption with breast cancer risk.

Natural history of soy allergy and/or intolerance in children, and clinical use of soy-protein formulas

Atopic diseases of infants and children are common, debilitating, chronic and sometimes even life-threatening. Several well-conducted studies in high risk babies have demonstrated a significant reduction in the prevalence and severity of atopic diseases with dietary and environmental manipulations. The currently available cow's milk (CM) substitutes for infants are soy protein (SP) formulas (SPFs), hydrolyzed formulas (HF), and home-made meat-based formulas. Soybeans have been cultivated in Eastern countries for many centuries and were first used to feed US babies with CM allergy (CMA) in 1929. Since then, SPFs containing purified SP, a mixture of vegetable oils, and purified carbohydrate have been developed. From a nutritional point of view, SPFs are adequate, support normal growth, protein status, bone mineralization, are well accepted, and economical. SPFs are used for different conditions including CMA, lactose and galactose intolerance and in the management of severe gastroenteritis, and some studies show that feeding SPFs for the first six months of life significantly reduces the prevalence of atopic diseases in high risk babies. Although gastrointestinal symptoms and atopic dermatitis (AD) may occur in some SPF-fed children, anaphylaxis following the ingestion of soybean is extremely rare in children. However, in the past few years the antigenicity/allergenicity of SPFs has been over-emphasized in the medical literature. In this paper on the natural history of soy antigenicity/allergenicity we discuss all the pros and cons of SPFs, their composition and nutritional value, the basic immune definitions, chemistry and characterization of SPs. We then discuss the antigenicity and allergenicity of SPFs in animals, recent data on the use of SPFs and the incidence of soy allergy in children, clinical reactions to SPFs, and the clinical relevance of skin testing and IgE antibodies to soy, challenge test procedure, clinical indication of SPFs, and their relevance in the prevention of atopy. We have meta-analyzed 17 different studies and conclude that history-based SPF allergy incidence totals 27%, in skin prick tests (SPT) RAST-oral food challenge (OFC)/double-blind food challenge (DBFC)-based epidemiological studies attains 3%, and in challenge test studies 4%. We suggest that double-blind placebo-controlled food challenge (DBPCFC) studies in larger cohorts of babies may establish a more reliable prevalence of SPF allergy in different disorders associated with CMA.

Fecal alpha 1-antitrypsin in newborn infants

BACKGROUND

Fecal alpha 1-antitrypsin is used as a marker for intestinal protein loss reflecting increased intestinal permeability. Exact data of fecal alpha 1-antitrypsin in newborn infants are not available.

METHODS

30 healthy mature neonates and three infants with impaired gastrointestinal passage due to stenoses and atresia respectively, were investigated during the first days of life. The amniotic fluid of 13 and the serum of 17 infants was available. alpha 1-antitrypsin was determined using the radial immunodiffusion method.

RESULTS

Normal newborns showed mean fecal alpha 1-antitrypsin levels (+/-SD) of 2061 +/- 817 mg/dl (day 1), 1186 +/- 720 mg/dl (day 2), 308 +/- 380 (day 3), 35 +/- 27 (day 5), and 27 +/- 21 mg/dl (day 6). Two infants with esophageal atresia presented a much lower pattern, and one with annular pancreas had a fecal alpha 1-antitrypsin pattern comparable with that of normal babies. Serum alpha 1-antitrypsin was normal (275 +/- 52 mg/dl), and amniotic fluid contained 20 +/- 12 mg/dl alpha 1-antitrypsin.

CONCLUSIONS

The pattern of neonatal fecal alpha 1-antitrypsin content appears to reflect the meconium clearance of the gut rather than intestinal permeability and "gut closure." We hypothesize that the origin of increased fecal alpha 1-antitrypsin is the result of accumulated secretions from bile, the pancreas, and the duodenum, but alpha 1-antitrypsin originating from swallowed amniotic fluid during pregnancy may play an additional role.

Increased frequency of IgM antibodies to cow's milk proteins in Hungarian children with newly diagnosed insulin-dependent diabetes mellitus

We investigated the association between serum antibodies to cow's milk proteins and insulin-dependent diabetes mellitus (IDDM) in Hungarian children. Forty-eight children 1.0-17.1 years of age with newly diagnosed IDDM and 74 control children 1.0-16.0 years of age were studied for serum IgG, IgA and IgM antibodies to cow's milk, beta-lactoglobulin, bovine serum albumin and ovalbumin by enzyme-linked immunosorbent assays. The specificity of IgM antibodies to beta-lactoglobulin and bovine serum albumin was controlled by Western blot. The levels of IgG and IgA antibodies to cow's milk proteins were similar in children with and without IDDM, with the exception of slightly increased levels of IgA antibodies to beta-lactoglobulin in diabetic children (P = 0.05). The levels of IgM antibodies to cow's milk were significantly higher in IDDM patients than in control children (P = 0.0002). Children with IDDM more often had IgM antibodies to beta-lactoglobulin (46.3% vs 18.8%; P = 0.002) and bovine serum albumin (87.8% vs 49.3%, P < 0.0001) than control children. Neither the levels of IgG or IgA antibodies to ovalbumin nor the frequency of IgM antibodies to ovalbumin differed between diabetic and control children.

CONCLUSION

In Hungarian children, clinical manifestation of IDDM is often associated with IgM antibody response to cow's milk protein and its fractions, beta-lactoglobulin and bovine serum albumin, indicating a loss of immunological tolerance to these proteins. IgG and IgA antibodies to cow's milk proteins, associated with an early introduction of cow's milk in diet, seem to play a minor role in the development of childhood IDDM in Hungary.

Uptake of antigens: role in gastrointestinal disease

The intestine is exposed to a wide variety of macromolecules. Because macromolecules are antigenic, mechanisms have evolved in the gastrointestinal tract to regulate their absorption. Macromolecular uptake can be beneficial in delivering essential factors for growth and in sampling the antigenic milieu of the gastrointestinal tract. Specific transport mechanisms exist to execute this physiological absorption. However, inappropriate and uncontrolled antigen transport may occur in disease states, or as a prelude to disease states in the gastrointestinal tract. Such transport may result in immune responses that are harmful. In this review we examine both physiological transport of macromolecules through epithelia and through M cells. We also discuss uncontrolled transport and its relation to disease states. We conclude by examining the interrelationship between antigen transport and an altered immune system in the establishment of gastrointestinal disease.

Implications of antinutritional components in soybean foods

There are a number of components present in soybeans that exert a negative impact on the nutritional quality of the protein. Among those factors that are destroyed by heat treatment are the protease inhibitors and lectins. Protease inhibitors exert their antinutritional effect by causing pancreatic hypertrophy/hyperplasia, which ultimately results in an inhibition of growth. The lectin, by virtue of its ability to bind to glycoprotein receptors on the epithelial cells lining the intestinal mucosa, inhibits growth by interfering with the absorption of nutrients. Of lesser significance are the antinutritional effects produced by relatively heat stable factors, such as goitrogens, tannins, phytoestrogens, flatus-producing oligosaccharides, phytate, and saponins. Other diverse but ill-defined factors appear to increase the requirements for vitamins A, B12, D, and E. The processing of soybeans under severe alkaline conditions leads to the formation of lysinoalanine, which has been shown to damage the kidneys of rats. This is not generally true, however, for edible soy protein that has been produced under milder alkaline conditions. Also meriting consideration is the allergenic response that may sometimes occur in humans, as well as calves and piglets, on dietary exposure to soybeans.

Allergic proctocolitis in infants: a prospective clinicopathologic biopsy study

Allergic proctocolitis is a major cause of rectal bleeding in infants, but its clinical features and laboratory results are often nonspecific. Our previous retrospective study demonstrated that large numbers of eosinophils in colonic mucosal biopsy specimens were highly associated with cases of allergic proctocolitis. Therefore, we prospectively examined 60 colonic mucosal biopsy specimens from the same sites (4, 8, and 12 cm from the anal verge) in 20 infants with clinically confirmed allergic proctocolitis to validate this morphologic feature, to characterize its distribution, and to correlate these data with the clinical information. The patients (age range, 4 to 304 days) were fed breast milk or a variety of formulas and all presented with rectal bleeding. Sigmoidoscopic examination was abnormal in 19 cases, typically characterized by focal areas of mucosal erythema. The major histologic finding was a strikingly focal increase in the number of eosinophils in all mucosal compartments, with a predilection to aggregate in close association with lymphoid nodules. Eosinophilic infiltration varied not only between biopsies at different sites, but also within individual biopsy specimens. Only 12 of 20 patients (60%) had all three of their biopsy specimens categorized as abnormal; in the remainder, only one (four patients) or two (four patients) of the three biopsy specimens were abnormal. The average number of eosinophils per high-power field of lamina propria for all cases was 15.6. No significant correlation was identified between the number of eosinophils in the mucosa and the patient's age, length of illness, endoscopic appearance, or type of inciting formula. In summary, eosinophils appear to be an excellent marker for infantile allergic proctocolitis. Given the focal distribution of the eosinophils, multiple mucosal biopsy specimens should be obtained and several levels of each examined to confirm the diagnosis.

In vitro allergenicity of cows' milk substitutes

There are numerous alternatives to cows' milk formula for allergic children. We have investigated the allergenicity of several of these using RAST and RAST inhibition on serum from 16 patients with a known history of cows' milk protein intolerance (CMPI) and 16 atopic controls. A RAST grade of > or = 3 for cows' milk was present in all those with CMPI, whilst all the controls gave RAST of < or = 1. Modified cows' milk formula, goats' infant formula, sheep and goats' milk produced similar results to cows' milk. Only two patients had RAST > or = 3 for soya milk and the soy/beef hydrolysate gave positive results in only three patients. One had positive RAST to Nutramigen and two to Pregestimil. Of the whey hydrolysates investigated, Pepti-junior gave seven positive RASTs whilst we were unable to bind Alfare to the sepharose in sufficient quantities to interpret the results which were negative in all cases. RAST inhibition data on pooled sera from the same patients agreed with the RAST results. The inhibition curves showed high inhibition with goats', sheep, modified cows' milk formula and the casein formula, AL110 (50%). Soy and soy/beef hydrolysate showed a much lower inhibition pattern. Casein hydrolysates showed low inhibition while the whey hydrolysate produced higher inhibition. We have shown that despite claims of low allergenicity, some of these alternative formulae are antigenically recognized in vitro by some cows' milk intolerant patients.

Uptake and transport of macromolecules by the intestine: possible role in clinical disorders (an update)

The intestine is exposed to a wide variety of macromolecules. Because macromolecules are antigenic, mechanisms have evolved in the gastrointestinal tract to regulate their absorption. Macromolecular uptake can be beneficial in delivering essential factors for growth and in sampling the antigenic milieu of the gastrointestinal tract. Specific transport mechanisms exist to execute this physiological absorption. However, inappropriate and uncontrolled antigen transport may occur in disease states or as a prelude to disease states in the gastrointestinal tract. Such transport may result in immune responses that are harmful. This review examines physiological transport of macromolecules through epithelia and through M cells. It also considers uncontrolled transport and its relation to disease states. The review concludes with an examination of the interrelationship between antigen transport and an altered immune system in the establishment of gastrointestinal disease.

Allergenicity and nutritional adequacy of soy protein formulas

Soy protein formulas are used for different conditions, including cow milk protein allergy, lactose and galactose intolerance, and severe gastroenteritis. Feeding soy protein formulas to normal term infants is associated with normal growth, normal protein nutritional status, and normal bone mineralization. Recent studies of infants fed soy protein formulas exclusively during the first months of life revealed no immunologic abnormality; however, the use of such formulas for management of cow milk protein allergy and for prevention of atopy is controversial. Although in the past decade many studies have stressed soy allergenicity, soy allergenicity has been confirmed by the challenge test in only a few studies. In this article we review the studies dealing with the allergenicity of soy protein formulas. We also present our own data on their use in the prevention and management of cow milk protein allergy.

The IgE and IgG subclass antibody response to foods in babies during the first year of life and their relationship to feeding regimen and the development of food allergy

This follow-up study of 191 babies investigated the development of food allergy in an unselected population and its relationship to total and antigen-specific IgE and IgG subclass levels. Sensitization to egg, as indicated by a positive skin test or RAST, was found in 5% of 1-year-old babies, but none of the babies in this series fulfilled the clinical criteria for immediate-type milk allergy. For both bovine casein (CAS) and egg albumin, the IgG response was largely restricted to IgG1 in contrast to the predominant IgG4 response to these antigens that is found in adults. The level of IgG4, but not IgG1, antibody to CAS and ovalbumin (OV) was lower in some of the babies compared with that of their mothers (N = 166; p less than 0.05, Student's paired t test). However, there was no difference in the total serum IgG subclass levels between mothers and babies. These results demonstrate that, in the population of babies studied, (1) type I hypersensitivity to egg occurred in 5% of 1-year-old babies, (2) the predominant IgG subclass of antibodies to CAS and OV in babies is IgG1, and (3) in the 22% of babies, there was substantially (greater than 1000-fold) less IgG4 antibody to CAS and OV than in their mothers, suggesting specific exclusion of some IgG4 antibodies.

Exaggerated intestinal histamine release by casein and casein hydrolysate but not whey hydrolysate

Loops of rabbit distal small intestine received luminal acetic acid (pH 4.0) alone or in combination with bovine casein, casein hydrolysate, or whey hydrolysate. Blood-to-lumen movement of 51Cr-labeled ethylenediaminetetraacetic acid (EDTA) (an index of epithelial permeability) and loop fluid histamine levels were quantified after 45 min. Luminal acetic acid caused a marked increase in 51Cr-EDTA accumulation which was not modified by the addition of bovine casein or hydrolysates by of casein or whey. However, acetic acid-induced histamine release was potentiated by casein and casein hydrolysate (six- and four-fold respectively) but was not altered by whey hydrolysate. Casein hydrolysate-dependent histamine release was evident in naloxone-pretreated rabbits, suggesting that beta-casomorphins were not solely responsible. We conclude that luminal casein or casein hydrolysate, but not whey hydrolysate. can activate intestinal mast cells under conditions of enhanced epithelial permeability. This effect appears to involve components other than beta-casomorphins.

Nutritional therapy for infants with diarrhea

The appropriate choice of treatment for infants with diarrhea has long provoked debate. Growth of infants with diarrhea is adversely affected by associated diseases including anorexia, malabsorption, catabolic response to infection, and iatrogenic starvation. To prevent the negative effects of diarrhea on the nutrition of infants, continued feeding during the active and early convalescent phases has been recommended. Although this concept is not new, until recently it has been little used in the treatment of diarrhea. In this article we examine the current knowledge about, and trends in, feeding infants with diarrhea. We will discuss treatments for the well-nourished infant with acute diarrhea, the infant with prolonged diarrhea, and the malnourished infant. Information regarding the use of local staples will also be provided.

Bovine growth hormone: human food safety evaluation

Scientists in the Food and Drug Administration (FDA), after reviewing the scientific literature and evaluating studies conducted by pharmaceutical companies, have concluded that the use of recombinant bovine growth hormone (rbGH) in dairy cattle presents no increased health risk to consumers. Bovine GH is not biologically active in humans, and oral toxicity studies have demonstrated that rbGH is not orally active in rats, a species responsive to parenterally administered bGH. Recombinant bGH treatment produces an increase in the concentration of insulin-like growth factor-I (IGF-I) in cow's milk. However, oral toxicity studies have shown that bovine IGF-I lacks oral activity in rats. Additionally, the concentration of IGF-I in milk of rbGH-treated cows is within the normal physiological range found in human breast milk, and IGF-I is denatured under conditions used to process cow's milk for infant formula. On the basis of estimates of the amount of protein absorbed intact in humans and the concentration of IGF-I in cow's milk during rbGH treatment, biologically significant levels of intact IGF-I would not be absorbed.

[The immunogenicity and allergenicity of an experimental cow's milk protein hydrolysate]

Recently hydrolyzed cow milk proteins have been introduced for the production of infant formulas and are available as hypoallergenic infant formulas. To achieve a decrease in antigenicity and allergenicity a protein hydrolysis (mostly enzymatic) is performed. Sera of different groups were tested for IgG and IgE antibody-binding: 31 controls, 36 atopic children, and 20 children with cow milk protein allergy. Histamine release from basophil leucocytes after incubation with the cow milk proteins beta-lactoglobuline and casein, as with the cow milk protein hydrolysate, was determined additionally for five control, 10 atopic, and five cow milk allergic children. IgG binding to cow milk protein and to the hydrolysate was found in the majority of the sera tested. IgE binding was detectable in sera of only five of the 10 cow milk allergic children, despite detection of specific IgE-antibodies against cow milk proteins in all sera. Histamine release by the cow milk hydrolysate was observed for five atopic and two cow milk allergic children. The cow milk hydrolysate demonstrated a decreased but partially conserved antigenic/allergenic potency compared with cow milk proteins.

Antibody response to milk proteins in patients with milk-protein intolerance documented by challenge

To evaluate the role of specific antibody response to milk proteins in patients with milk-protein intolerance, allergen-specific IGE, IgG, and IgG4 to these proteins were measured by ELISA. Bovine casein, gamma globulin (GG), beta-lactoglobulin, and lactalbumin were the milk proteins used. Antibody production to these proteins were analyzed in 18 patients who underwent milk-protein challenges (eight positive and 10 negative) and in five normal children used in the analysis. ELISA results for specific IgE, IgG, and IgG4 to these specific proteins demonstrated no statistically different response to the four milk proteins among the three patient groups by multivariate analysis. When the specific antibody results from the positive challenge group, the negative challenge group, and the normal group were combined, the IgE and IgG4 to GG and the IgG to casein were significantly higher (p less than 0.01) than the corresponding specific antibody to the other proteins tested. The IgG or IgG4 to GG would differentiate the positive from the negative challenge group (p less than 0.05) but were not significantly different from the normal control group. Contrary to previously published studies, these results indicate IgG specific for the milk proteins are not increased in patients with milk-protein intolerance. The data also support the concept that IgE and IgG4 are not elevated in these patients. Therefore, there appears to be no pathogenic role for these specific immunoglobulins in milk-protein intolerance.

Severe cow's milk induced colitis in an exclusively breast-fed neonate. Case report and clinical review of cow's milk allergy

Cow's milk induced eosinophilic colitis presenting in the first week of life has been reported, but is very rare. The authors describe a 4-day-old female infant who presented with profuse rectal bleeding resulting in a hematocrit fall from 38% to 30% within 8 hr after hospital admission. Sigmoidoscopy revealed colonic mucosa that was red, edematous, and friable, with punctate hemorrhages. Rectal biopsy showed marked eosinophilic infiltration with multifocal hemorrhage. Further history indicated that while the infant had been exclusively breast-fed since birth, the nursing mother had been drinking 4-5 glasses of cow's milk per day since delivery. Prick puncture skin testing of the infant was positive for cow's milk protein. A serum radioallergosorbent test (RAST) for cow's milk protein was positive. The infant's serum IgE was 1.5 IU/ml. Rectal bleeding resolved when the patient was given a casein hydrolysate formula (Nutramigen, Mead Johnson Nutrition, Evansville, IN), and endoscopy one week later showed improvement, with only scattered areas of erythema, and no friability. We conclude that since the infant was exclusively breast-fed, the milk protein must have passed into the breast milk antigenically intact. Prenatal sensitization probably occurred. Cow's milk induced allergic colitis should be considered in the differential diagnosis of colitis in breast-fed neonates.

A long-term metabolic study to assess the nutritional value of and immunological tolerance to two soy-protein concentrates in adult humans

Seventeen healthy young adult men participated in a long-term metabolic study (11 wk) to evaluate the tolerance to and protein nutritional value of two commercially produced soy-protein concentrates. Danpro-S (nine subjects) and Danprotex-H 40 (eight subjects) (Aarhus Oliefabrik A/S, Aarhus, Denmark). Each test protein (0.8 g.kg-1.d-1) served as the sole source of dietary nitrogen. Subjects remained healthy, no problems of clinical or metabolic significance appeared, body weight remained constant, and body composition indices (lean body mass by H2(18)O dilution and creatinine excretion) and basal metabolic rate did not change. N balances fluctuated around body N equilibrium. Immunological studies confirmed the absence of any allergic responses in these subjects. It is concluded that these protein concentrates can be consumed as the sole source of dietary protein for protein nutritional maintenance and with excellent tolerance.

Macromolecular absorption in preterm and term infants

Human alpha-lactalbumin (alpha-LA) has been used as a marker for measuring macromolecular absorption. The serum concentration of human alpha-LA after a human milk feed has been studied in 32 healthy very low birthweight infants (VLBW), fed human milk (gestational age 26-32 weeks) and in 56 term, breast-fed infants, age 3-140 days. At 31 weeks of gestation the serum concentration of human alpha-LA was more than 10 times higher (mean value 3,000 and median value 2,101 micrograms/l serum/l human milk/kg body weight, n = 11) than in the term infants aged 3-30 days (mean value 257 and median value 152, n = 29). The serum concentration of alpha-LA decreased with increasing maturity in the VLBW-infants. At a postconceptional age of 37 weeks the values were similar (mean value 200 and median value 99, n = 8) to those found for term infants during the first month. In the term infants a decreasing absorption of alpha-LA was found with increasing postnatal age.

Feeding the premature and compromised infant: gastrointestinal considerations

We have presented the current concepts of gastrointestinal ontogeny--the various factors governing the ontogeny of the gastrointestinal tract and the interaction and intricate relationship between different determinants. It is only through a better understanding of the development of the gut and the various factors affecting it that pediatric gastroenterologists are able to design nutritional support strategies for managing very young and compromised neonates.