Detection of potentially allergenic material in 12 hydrolyzed milk formulas

Allergenicity of partially hydrolyzed whey and casein formulas evaluated by ImmunoCAP inhibition assay and basophil activation test

Background

When exclusive breastfeeding is not possible, partially hydrolyzed formula (PHF) is often used as a starter formula for infants. Some children develop allergic symptoms, including anaphylaxis, after the first intake of cow protein. Therefore, the tolerability of PHF in infants with cow's milk allergy (CMA) is important information. Partially hydrolyzed whey formula (PHWF) is well characterized, but those containing both whey and casein are also available. We evaluated the characteristics of two whey and casein PHFs, PHF1 and PHF2, in vitro and ex vivo, and compared them with a PHWF, PHWF1.

Methods

Residual antigenicity of β-lactoglobulin (β-LG) and casein in the formulas was measured using ELISA. The molecular weight profile was determined using high-pressure liquid chromatography. IgE reactivity and allergenic activity of the formulas were evaluated by ImmunoCAP inhibition assay and by basophil activation test using blood from patients with CMA, respectively.

Results

All the participants (n = 10) had casein-specific IgE. The antigenicity of β-LG in PHF1 was similar to that in PHWF1, but it was slightly higher than that in PHWF1 for casein. PHF1 had a higher IgE reactivity than PHWF1. However, PHF1 and PHWF1 had a similar ability to activate basophils. PHF2 had lower antigenicity of casein and β-LG, IgE reactivity and basophil activation than PHWF1.

Conclusion

These results suggest that the tolerability of PHF1 and PHF2 in patients with CMA is similar to and higher than that of PHWF1, respectively, and that the degree of IgE binding to PHFs does not necessarily correspond to basophil activation.

Exploration of Specific Nanobodies As Immunological Reagents to Detect Milk Allergen of β-Lactoglobulin without Interference of Hydrolytic Peptides

Milk proteins are widely used for food supplementation, despite the potential risk of food allergy, especially against β-lactoglobulin (BLG), which makes BLG surveillance critical. Possible interaction of detecting antibodies with BLG-derived peptides will result in unprecise inspection. Thus, in this study, it was proposed to generate nanobodies (Nbs) and validate the immunological detection of intact BLG rather than hydrolytic peptides. Nbs were successfully retrieved and characterized with high stability and target specificity. A competitive enzyme-linked immunosorbent assay (cELISA) was developed with a linear range from 39 to 10,000 ng/mL and a detection limit (LOD) of 4.55 ng/mL, with a recovery of 86.30%-95.09% revealed by analysis of spiked samples. Meanwhile, a sandwich ELISA (sELISA) was established with Nb82 and BLG polyclonal antibody (pAb-BLG) providing a linear range from 29.7 to 1250 ng/mL and an LOD of 13.82 ng/mL with a recovery of 87.82%-103.97%. The interaction of selected Nbs with BLG-derived peptides was investigated by Nb structure modeling and BLG docking. No binding on hydrolytic peptides was revealed, confirming the precision of Nb-mediated immunoassays. In summary, this study successfully identified BLG-specific Nbs for immunoassay development and guaranteed the monitoring of intact BLG without interference of hydrolytic peptides, providing experimental evidence that our Nbs recognize intact food allergen.

Alternatives to Cow’s Milk-Based Infant Formulas in the Prevention and Management of Cow’s Milk Allergy

Cow’s milk-based infant formulas are the most common substitute to mother’s milk in infancy when breastfeeding is impossible or insufficient, as cow’s milk is a globally available source of mammalian proteins with high nutritional value. However, cow’s milk allergy (CMA) is the most prevalent type of food allergy among infants, affecting up to 3.8% of small children. Hypoallergenic infant formulas based on hydrolysed cow’s milk proteins are commercially available for the management of CMA. Yet, there is a growing demand for more options for infant feeding, both in general but especially for the prevention and management of CMA. Milk from other mammalian sources than the cow, such as goat, sheep, camel, donkey, and horse, has received some attention in the last decade due to the different protein composition profile and protein amino acid sequences, resulting in a potentially low cross-reactivity with cow’s milk proteins. Recently, proteins from plant sources, such as potato, lentil, chickpeas, quinoa, in addition to soy and rice, have gained increased interest due to their climate friendly and vegan status as well as potential lower allergenicity. In this review, we provide an overview of current and potential future infant formulas and their relevance in CMA prevention and management.

Determination of Casein Allergens in Extensively Hydrolyzed Casein Infant Formula by Liquid Chromatography-Tandem Mass Spectrometry

BACKGROUND

The use of hypoallergenic infant formulas and the need for reliable tests to determine the presence of residual antigens have increased in parallel.

OBJECTIVE

An LC-MS method for quantitation of casein was validated using incurred samples and a matrix-matched external standard curve.

METHOD

Powdered infant formula samples were extracted in a buffer of sodium deoxycholate and ammonium bicarbonate at 60°C and filtered through 7 kDa desalting columns. Samples were digested overnight with trypsin and precipitated with acid prior to analysis of marker peptides by tandem mass spectrometry.

RESULTS

Based on three marker peptides, the linear range for casein was 1.8-42 μg/g of powdered infant formula with an LOQ of 1.8 μg/g. The determination coefficients (R2) for each curve were ≥0.99 for casein peptides. Method repeatability was ≤22% RSD and intermediate precision was ≤23% RSD; recovery of casein from incurred material (2-20 µg/g) ranged from 78% to 118%.

CONCLUSIONS

An LC-MS/MS method was developed and validated for confirmation of casein allergens in hypoallergenic infant formula.

HIGHLIGHTS

A method was developed to accurately and reliably quantify casein allergens in extensively hydrolyzed casein infant formula by LC-MS without the need for custom peptide standards.

Design, quality, safety and efficacy of extensively hydrolyzed formula for management of cow's milk protein allergy: What are the challenges?

Cow's milk protein allergy (CMPA) is one of the most common food allergies in infancy. Clinical food allergy guidelines recommend an extensively hydrolyzed formula (EHF) as the first-line treatment in nonbreastfed infants with CMPA. Designing and commercializing EHF poses both technical and regulatory challenges. Each manufacturing step, from sourcing of raw materials to release of the final product, needs to be managed in accordance with comprehensive quality systems. To avoid cross-contamination via externally sourced ingredients, suppliers should be carefully selected based on quality requirements. Strict zoning of the manufacturing areas according to contamination risk and air flow control are effective strategies to prevent accidental allergen contamination. Furthermore, dedicated manufacturing lines for hypoallergenic products are used to prevent potential cross-contamination from other products produced on the same line. The enzymatic hydrolysis, heat treatment and ultrafiltration used are specific to each manufacturer. Consequently, EHF are a heterogenous group of products with differences in the molecular weight profile of peptides, content of residual immunogenic cow's milk allergens, and residual in-vitro allergenicity. These differences are likely to affect clinical efficacy and safety. As not all commercialized EHF products have undergone formal testing in the laboratory and clinical trials, there is a need to develop guidelines for minimum technical and regulatory requirements for EHF products, including validated assays for ongoing quality control. Clinical trials assessing new EHF products for their hypoallergenicity and ability to support normal growth remain the definitive proof of efficacy and safety in infants and young children with CMPA.

Epicutaneous immunogenicity of partially hydrolyzed whey protein evaluated using tape-stripped mouse model

BACKGROUND

Hydrolyzed cow's milk protein formulas are widely used for infants with a history or risk of cow's milk allergy. Based on the current theory that food allergen sensitization occurs via the skin, we investigated the epicutaneous immunogenicity of partially hydrolyzed whey proteins, which are ingredients in infant formulas.

METHODS

BALB/c mice were exposed epicutaneously to whey protein concentrate (WPC) or partial whey protein hydrolysates (PWH1 or PWH2) on tape-stripped skin. Sensitization was assessed by evaluating serum β-lactoglobulin (β-LG)-specific antibodies, basophil activation, and cytokine production from β-LG-stimulated lymphoid cells. The anaphylaxis reaction was evaluated by measuring the rectal temperature and plasma level of mouse mast cell protease-1 after oral β-LG challenge. Immune cell accumulation in the skin was also analyzed.

RESULTS

Substantive sensitization and β-LG-induced anaphylaxis reaction were observed in WPC-exposed mice, whereas no significant changes were observed in PWH1- or PWH2-exposed mice. The basophil and eosinophil counts increased in WPC-exposed murine skin, not but in PWH1- or PWH2-exposed mice.

CONCLUSION

The epicutaneous immunogenicity of PWH1 and PWH2 is markedly decreased, which may reduce the risk of allergen sensitization. Further studies are required to investigate the clinical value of these partial hydrolysates for high-risk infants.

An update to the Milk Allergy in Primary Care guideline

The Milk Allergy in Primary (MAP) Care guideline was first published in 2013 in this journal. MAP aimed to provide simple and accessible algorithms for UK clinicians in primary care, detailing all the steps between initial presentation, through diagnosis, management and tolerance development. Despite its UK focus, it soon became clear that MAP was being accessed internationally and thus an updated International Milk Allergy in Primary Care (iMAP) guideline was published in 2017. Both guidelines used existing international consensus guidelines to develop accessible algorithms accompanied by patient information leaflets. In 2018, the guidelines were criticised for 3 distinct reasons: promoting the overdiagnosis of cow's milk allergy (CMA), negatively impacting breastfeeding and the possibility of industry influence on the guidelines. The authors address these criticisms using available evidence and, in the context of this and in consultation with patient groups, members of the General Practice Infant Feeding Network and other infant feeding healthcare leads, have collaboratively produced updated algorithms and an information leaflet to support breastfeeding. We believe iMAP is now closer to its original aim of facilitating early and accurate diagnosis of CMA, whilst minimising, as far as possible, any concerns around overdiagnosis or a risk to breastfeeding rates. We continue to welcome open and constructive engagement about how best to achieve these aims to provide evidence-based, practical guidelines for the primary care practitioner.

Impact of enzymatic hydrolysis followed by transglutaminase-induced cross-linking on decreasing antigenicity and reserving partial interfacial properties of whey protein isolate

Whey protein isolate (WPI) was hydrolyzed by alcalase and trypsin for three hydrolysis degrees (DHs), followed by transglutaminase (TGase) induced cross-linking.

A two-step enzymatic modification method to reduce immuno-reactivity of milk proteins

A two-step enzymatic approach to reduce immuno-reactivity of whey protein isolate and casein has been studied. The method involves partial hydrolysis of proteins with proteases, followed by repolymerization with microbial transglutaminase. Whey protein isolate partially hydrolyzed with chymotrypsin, trypsin, or thermolysin retained about 80%, 30%, and 20% of the original immuno-reactivity, respectively. Upon repolymerization the immuno-reactivity decreased to 45%, 35%, and 5%, respectively. The immuno-reactivity of hydrolyzed and repolymerized casein was negligible compared to native casein. The repolymerized products were partially resistant to in vitro digestion. Peptides released during digestion of repolymerized thermolysin-whey protein hydrolysate had less than 5% immuno-reactivity, whereas those of whey protein control exhibited a sinusoidal immuno-reactivity ranging from 5 to 20%. Peptides released during digestion of repolymerized thermolysin-casein hydrolysates had no immuno-reactivity. These results indicated that it is possible to produce hypoallergenic milk protein products using the two-step enzymatic modification method involving thermolysin and transglutaminase.

Digestibility of transglutaminase cross-linked caseinate versus native caseinate in an in vitro multicompartmental model simulating young child and adult gastrointestinal conditions

Aim of this study was to investigate the digestion of transglutaminase cross-linked caseinate (XLC) versus native caseinate (NC) in solution and in cheese spread under digestive conditions for adults and children mimicked in a gastrointestinal model. Samples were collected for gel electrophoresis and nitrogen analysis. The results showed no relevant differences between XLC and NC for total and α-amino nitrogen in digested fraction under adult and child conditions. However, the rate of digestion was depending on the food matrix. Gel electrophoresis showed the gastric breakdown of XLC without formation of pepsin resistant peptides larger than 4 kDa. NC was slowly digested in the stomach with formation of pepsin resistant fragments and was still detectable in the stomach after 90 min. In the small intestine the proteins were rapidly digested. XLC was digested to small peptides, while NC was resistant against pepsin digestion under gastric conditions of adults and children.

Diagnosis and management of non-IgE-mediated cow's milk allergy in infancy - a UK primary care practical guide

The UK NICE guideline on the Diagnosis and Assessment of Food Allergy in Children and Young People was published in 2011, highlighting the important role of primary care physicians, dietitians, nurses and other community based health care professionals in the diagnosis and assessment of IgE and non-IgE-mediated food allergies in children. The guideline suggests that those with suspected IgE-mediated disease and those suspected to suffer from severe non-IgE-mediated disease are referred on to secondary or tertiary level care. What is evident from this guideline is that the responsibility for the diagnostic food challenge, ongoing management and determining of tolerance to cow’s milk in children with less severe non-IgE-mediated food allergies is ultimately that of the primary care/community based health care staff, but this discussion fell outside of the current NICE guideline. Some clinical members of the guideline development group (CV, JW, ATF, TB) therefore felt that there was a particular need to extend this into a more practical guideline for cow’s milk allergy. This subset of the guideline development group with the additional expertise of a paediatric gastroenterologist (NS) therefore aimed to produce a UK Primary Care Guideline for the initial clinical recognition of all forms of cow’s milk allergy and the ongoing management of those with non-severe non-IgE-mediated cow’s milk allergy in the form of algorithms. These algorithms will be discussed in this review paper, drawing on guidance primarily from the UK NICE guideline, but also from the DRACMA guidelines, ESPGHAN guidelines, Australian guidelines and the US NIAID guidelines.

Dietary treatment of cows' milk protein allergy in childhood: a commentary by the Committee on Nutrition of the French Society of Paediatrics

The diagnosis of cows' milk protein allergy (CMPA) requires first the suspicion of diagnosis based on symptoms described in the medical history, and, second, the elimination of cows' milk proteins (CMP) from the infant's diet. Without such rigorous analysis, the elimination of CMP is unjustified, and sometimes harmful. The elimination diet should be strictly followed, at least until 9–12 months of age. If the child is not breast fed or the mother cannot or no longer wishes to breast feed, the first choice is an extensively hydrolysed formula (eHF) of CMP, the efficacy of which has been demonstrated by scientifically sound studies. If it is not tolerated, an amino acid-based formula is warranted. A rice protein-based eHF can be an alternative to a CMP-based eHF. Soya protein-based infant formulae are also a suitable alternative for infants >6 months, after establishing tolerance to soya protein by clinical challenge. CMPA usually resolves during the first 2–3 years. However, the age of recovery varies depending on the child and the type of CMPA, especially whether it is IgE-mediated or not, with the former being more persistent. Once the child reaches the age of 9–12 months, an oral food challenge is carried out in the hospital ward to assess the development of tolerance and, if possible, to allow for the continued reintroduction of CMP at home. Some children with CMPA will tolerate only a limited daily amount of CMP. The current therapeutic options are designed to accelerate the acquisition of tolerance thereof, which seems to be facilitated by repeated exposure to CMP.

Evaluation of an extensively hydrolysed casein formula (Damira 2000) in children with allergy to cow's milk proteins

OBJECTIVE

To assess the allergenic capacity of a new extensively hydrolysed casein formula (Damira 2000) in vivo in children with allergy to cow's milk, and to conduct an immunochemical evaluation of the product.

PATIENTS AND METHODS

The study comprised 67 children (1 month-7 years) with allergy to cow's milk proteins (ACMP). Skin testing was made with whole milk, milk formula for infants, the study hydrolysate and the milk fractions (alpha-lactoalbumin, beta-lactoglobulin and casein). Specific IgE against these allergens, and oral provocation test were also performed. Immunochemical evaluation of the product was carried out with gel filtration chromatography, 4-15% acrylamide gradient gel electrophoresis, specific IgE quantification versus the casein hydrolysate and a study of its allergenic potency.

RESULTS

The hydrolysate was tolerated by 66 of the 67 patients (98.5%) with ACMP. Biochemical analysis of the product confirmed the absence of traces of whole milk proteins. Specific IgE against the hydrolysate proved negative in all cases, and it was unable to inhibit FEIA even at concentrations 10 times greater than those used in the whole milk inhibition control. Likewise, no immunoblotting inhibition was recorded.

CONCLUSIONS

The new extensively hydrolysed casein product is safe and well tolerated by most children with ACMP. However, as with other extensive hydrolysates, some highly sensitised patients may present clinical manifestations. Controlled tolerance testing is therefore advised, under specialised medical supervision.

Factors influencing the incidence and prevalence of food allergy

Food allergy is an increasing problem in Europe and elsewhere and severe reactions to food are also becoming more common. As food allergy is usually associated with other forms of allergic sensitisation it is likely that many risk factors are common to all forms of allergy. However the potential severity of the disease and the specific public heath measures required for food allergy make it important to identify the specific risk factors for this condition. Food allergy is unusual in that it often manifests itself very early in life and commonly remits with the development of tolerance. Hypotheses that explain the distribution of food allergy include specific genetic polymorphisms, the nature of the allergens involved and the unique exposure to large quantities of allergen through the gut. Progress has been made in developing more specific and testable hypotheses but the evidence for any of these is still only preliminary. Further collaborative research is required to develop an appropriate public health response to this growing problem.

Selection of recombinant IgE antibodies binding the beta-lactoglobulin allergen in a conformation-dependent manner

Cow's milk allergy (CMA) is a common food allergy, especially among infants and young children. Approximately 85% of milk-allergic children outgrow their allergy by the age of three but the remaining 15% remain allergic. Bovine beta-lactoglobulin (BLG) is one of the major allergens in cow's milk. There is a definite need for the specific and sensitive detection of allergenic substances. Validated methods are obligatory to demonstrate allergen contamination and even fatal hidden allergens and, thus, to prevent life-threatening conditions of allergic persons. In this study, we constructed human IgE scFv libraries from an adult milk-allergic patient and isolated the first recombinant IgE antibodies specific to a food allergen, BLG. The selection of the IgE antibody libraries with two distinct panning procedures resulted in the enrichment of four clones having different BLG-binding profiles; two of the clones recognize the native BLG whereas the other two recognize only the heat-denatured form of BLG. For further characterization, the scFv fragments were converted to Fab fragments with human IgG1 isotype. The D1 Fab fragment, binding native BLG with nanomolar affinity, also partially inhibited serum IgE binding to BLG. These BLG-specific IgE antibodies can be applied for the detection of both native and denatured BLG in cow's milk products and furthermore, for the optimization of manufacturing processes to develop safe hypoallergenic milk products.

Hypoallergenic formulas: optimal choices for treatment versus prevention

OBJECTIVES

To provide information on certain formulas that are relevant to allergy practice, focusing on their protein source and allergenicity, and to provide recommendations for selecting an optimal formula, taking into consideration efficacy, safety, palatability, and cost.

DATA SOURCES

A literature search using the PubMed database for the following keywords: hypoallergenic formulas, infant formulas, hydrolysate formulas, elemental formulas, and amino acids formulas.

STUDY SELECTION

Information was derived from pertinent original studies and selected reviews, including recent Cochrane Database Systematic Reviews, published in the English-language literature.

RESULTS

For a formula to be considered hypoallergenic, it should be well tolerated by at least 90% of individuals who are allergic to the parent protein from which that formula has been derived. Extensively hydrolyzed formulas (EHFs), derived from bovine casein or whey, are tolerated by approximately 95% of cow's milk allergic individuals. Elemental formulas are prepared from synthesized free amino acids and are well tolerated practically by all individuals, including those who are allergic to EHFs. Partially hydrolyzed whey formula (PHWFs) cause allergy in one-third to half of milk allergic individuals and are not considered hypoallergenic. Both EHFs and PHWFs seem to be equally effective in reducing the risk of development of allergy in infants of atopic families.

CONCLUSION

The EHFs and amino acids formulas, but not the partially hydrolyzed formulas, are optimal for milk allergic individuals. All 3 types of formulas are useful for prevention. The cost and palatability should be considered in deciding which formula to use.

Immunological basis and management of food allergy

One of the most common allergies in children involves cow's milk, which contains approximately 20 different proteins that can cause allergic reactions. It is well known that children exhibiting signs of cow's milk allergy early in life often go on to develop allergy-related respiratory diseases; thus, management of early sensitisations and symptoms of food allergies is crucial to preventing subsequent allergic complications. Constant allergen exposure and other environmental factors determine whether a sensitised individual will become chronically allergic and experience persistent symptoms. Management of food allergies in children focuses on minimising sensitisation and encouraging immune system maturation through the exposure of children to exogenous stimuli known to prime the immune system. Hypoallergenic molecules or allergen avoidance can also be used to induce tolerance in allergy-prone children. Available evidence suggests that the onset of the sensitisation phase and the degree of inflammation can be modulated by external factors such as nutrition, and guidelines outlining the most effective dietary regimen for the prevention of allergic disease have been published. The underlying mechanisms of tolerance induction and the potential benefits of prophylactic treatment for food allergies remain to be determined.

Certain hydrolyzed formulas reduce the incidence of atopic dermatitis but not that of asthma: three-year results of the German Infant Nutritional Intervention Study

BACKGROUND

Recommendations for primary prevention of allergic diseases in high-risk children include feeding with hydrolyzed formulas if breast-feeding is insufficient.

OBJECTIVE

The primary objective of the German Infant Nutritional Intervention study was to investigate the allergy preventive effect of 3 hydrolyzed formulas compared with cow's milk formula in the first 3 years of life in a randomized, double-blind trial.

METHODS

Between 1995 and 1998, 2252 newborns with atopic heredity were allocated to a group receiving cow's milk formula, partially or extensively hydrolyzed whey formula, or extensively hydrolyzed casein formula as a milk substitute for the first 4 months if breast-feeding was insufficient. Main outcome parameters were allergic manifestations, atopic dermatitis (AD), and asthma.

RESULTS

After 3 years, 396 of 2252 children (17.6%) had dropped out. Breast-fed infants without formula feeding during the intervention (n = 889) were considered separately. A significant reduction of the incidence of AD was achieved with the extensively hydrolyzed casein formula in the intention-to-treat (ITT; n = 1363) and per protocol (PP; n = 904) analyses (ITT: population odds ratio [95% CI], 0.67 [0.45-0.99]; PP: adjusted odds ratio [OR(adj)], 0.53 [0.32-0.88]), and with the partially hydrolyzed whey formula in the PP analysis (ITT: population odds ratio, 0.76 [0.52-1.11]; PP:OR(adj), 0.60 [0.37-0.97]). None of the formulas reduced the incidence of asthma.

CONCLUSION

The risk for AD, but not for asthma, can be reduced with certain cow's milk hydrolyzates in high-risk infants when breast-feeding is insufficient.

CLINICAL IMPLICATIONS

Early nutritional intervention in high-risk children has significant influence on the incidence of AD, but not of asthma.

Human IgE binding to the glycosidic moiety of bovine kappa-casein

IgE ability for recognizing milk proteins was assayed in the serum of an adult atopic patient who outgrew cow milk allergy in early childhood. A number of protein species included in casein from bovine milk were detected by human IgE in immunoblotting experiments. Comparing these results with those obtained from an analysis using antibody preparations specifically directed toward the different casein fractions, IgE-reactive bands were identified as isoforms of kappa-casein. IgE-reactive protein was not present in neither bovine cheese, regardless of cheese-making technology and time ripening, nor milk from any other dairy animal, such as ewe, goat, and water buffalo. Chemical deglycosylation of protein bands immobilized onto nitrocellulose proved that the glycosidic moiety of bovine kappa-casein was principally involved in IgE recognition.

Analysis of trace amounts of bovine β-lactoglobulin in infant formulas by capillary electrophoresis with on-capillary derivatization and laser-induced fluorescence detection

Bovine beta-lactoglobulin (betaLG) has been described by several authors as the main allergen present in cow's milk. It can induce allergic reactions even at the low concentration existing in hypoallergenic formulas based on hydrolyzed cow's milk proteins (generally lower than microM). In this paper, the usefulness of a capillary electrophoresis method with on-capillary derivatization and laser-induced fluorescence detection for the analysis of trace amounts of betaLG in a commercial hypoallergenic formula has been demonstrated. To confirm the identity of the peak of betaLG based on migration time, an immunorecognition step employing an anti-betaLG antibody was performed. BetaLG was quantitated in the whey and casein fractions of the hypoallergenic formula. The concentration of betaLG in the whey fraction of the formula was about 3 orders of magnitude lower than the average value present in cow's milk. In the casein fraction of the formula, the concentration of betaLG was about 1 order of magnitude lower than in the whey fraction. The method developed was also used for the quality control of three cereal-based infant foods formulated without milk to test the presence or absence of betaLG as an indicator of milk contamination during the fabrication process. BetaLG in a concentration of 10(-7) M or higher was not observed in any of the cereal-based infant formulas analyzed.

Modification of IgE binding to beta-lactoglobulin by fermentation and proteolysis of cow's milk

The effect of fermentation by Lactobacilli and of proteolytic hydrolysis of whole milk on the IgE binding ability of beta-lactoglobulin was studied using an ELISA inhibition assay. Sera from nine adult milk allergic patients were tested. The individual sera showed a similar inhibition pattern in the changes during fermentation and proteolysis. The degradation of beta-lactoglobulin was studied with liquid chromatography. In general, fermentation with Lactobacilli gave little effect on IgE binding, even though chromatography data showed a gradual degradation of beta-lactoglobulin. Proteolysis with trypsin, however, gave extensive degradation of beta-lactoglobulin and strongly decreased IgE binding. In addition, we measured the inhibition pattern of beta-lactoglobulin in various selected commercially available fermented milk products. These showed an IgE binding capacity similar to that of nonfermented high pasteurized milk.

Hypoallergenic formulas--when, to whom and how long: after more than 15 years we know the right indication!

Hypoallergenic formulas are processed by enzymatic hydrolysis of different protein sources such as bovine casein/whey and soy followed by further processing such as heat treatment and/or ultrafiltration, or they are based on amino acid mixtures. The products have been classified according to the degree of protein hydrolysis as 'extensively' or 'partially' hydrolysed protein products. Product properties may be characterized by biochemical techniques, and reduction of allergenicity may be assessed in vitro with various immunological methods, and in vivo with skin prick tests, patch tests and challenge tests. In vitro tests do not predict the allergenic effects in humans, and at present there is no evidence of a specific threshold of immunogenic protein. Only pure amino acid mixtures are considered to be nonallergenic. Other 'hypoallergenic' products contain residual allergenicity. At present, the potential of a product for treatment and prevention of food allergy can only be determined by clinical trials using scientifically appropriate standards. It has been recommended that dietary products for treatment of cow's milk protein allergy in infants should be tolerated by at least 90% (with 95% confidence) of infants with documented cow's milk protein allergy. Some extensively hydrolysed products and amino-acid-based products have met these criteria. Formulas intended for prevention should have a very low, if any, allergenic activity until otherwise proven. So far there are no firm criteria available for the design of hypoallergenic foods for prevention. Newborns included in prevention studies should be from high-risk families; they should be randomized at birth and fed the formula when supplements are needed for at least the first 4-6 months of life. Follow-up should be at least 18 months, and children should be investigated when symptoms appear. Validated clinical criteria, including controlled food challenges, should be used for diagnosis. Infants fed formulas that claim to prevent or delay allergy should have a statistically significant lower prevalence of allergy when compared with infants fed a standard cow's milk formula. Feeding high-risk infants a documented hypoallergenic formula combined with avoidance of solid foods during the first 4-6 months reduces the cumulative incidence of cow's milk protein allergy and atopic dermatitis as compared with a standard cow's-milk-based formula. Partially hydrolysed formulas may have an effect, though it seems to be less than that of extensively hydrolysed formulas at present. Thus, if exclusive breast-feeding for 4-6 months is not possible in high-risk infants, a documented hypoallergenic formula and avoidance of solid foods are recommended for the first 4 months of life.

Modification of IgE binding during heat processing of the cow's milk allergen beta-lactoglobulin

The effect of heat treatment on the IgE binding ability of beta-lactoglobulin, as pure protein or in whole milk, was studied by inhibition of IgE antibody binding using FEIA-CAP inhibition. A slight but significant decreased IgE binding was seen between unheated and heat-treated beta-lactoglobulin solution at 74 degrees C (IC(50) = 2.03 and 3.59 microg/mL, respectively, p = 0.032). A more pronounced decrease was found at 90 degrees C with an IC(50) of 8.45 microg/mL (p = 0.014). The inhibition of IgE binding of milk after heat treatment at 90 degrees C was also significantly decreased (p = 0.007). However, at all heat treatments, a similar total amount of IgE antibodies could be inhibited at a sufficiently high concentration of beta-lactoglobulin. The inhibiting ability of beta-lactoglobulin was significantly impaired in some fermented acidified milk products such as yogurt as compared to that in nonfermented milk (p < 0.001). There was only a small difference of IgE binding between the native forms of genetic variants A and B.

Primary dietary prevention of food allergy

OBJECTIVE

To present research and clinical evidence on the use of primary dietary prevention in food allergy management.

DATA SOURCES

We conducted MEDLINE searches for pertinent articles published between January 1986 and October 2001 with use of the following keywords or phrases: prevention and diet and allergy, food allergy and prevention, and dietary prevention and food allergy or allergens. Also included are information and commentary reflecting the authors' cumulative clinical experience in an allergy unit of a city hospital.

RESULTS

We define as "proactive" those strategies centered on "success factors," such as the early postnatal environment, prolonged breast-feeding, and use of formula and probiotic supplementation, in contrast to earlier "prohibitionist" approaches to prevention of food allergy. These two approaches are not antagonistic and may even be synergistic. We introduce this distinction in light of epidemiologic evidence and out of concern about compliance and the quality of life for patients.

CONCLUSIONS

Inasmuch as nutritional and immune maturation are implicated, the prohibitionist measures that are most effective in primary prevention of food allergy are exclusive breast-feeding for at least 6 months (for lifelong immunity and other benefits), delayed (after the sixth month) introduction of solid foods, and on-indication use of "hypoallergenic" formulas. Whether proactive strategies can be contemplated remains a debatable issue. Evidence for and against the scientific use of probiotics as well as microbiologic, epidemiologic, and clinical data are discussed. Review of published epidemiologic studies and randomized clinical trials is essential before planning dietary intervention or prevention.

Safety of a new extensively hydrolysed formula in children with cow's milk protein allergy: a double blind crossover study

BACKGROUND

Formulae for infants with cow's milk protein allergy (CMA) should be based on extensively hydrolysed protein. 'Extensively' however is not strictly defined. Differences in molecular weight and peptide chain length may affect its clinical outcome. We studied the safety of a new extensively hydrolysed casein based formula (Frisolac Allergycare: FAC) for children with IgE mediated CMA.

METHODS

Thirty children, aged 1.5 - 14.8 years old (median 4.9 years) with persistent CMA were enrolled in this double-blind reference product (Nutramigen: NUT) controlled crossover study. All had positive skin prick tests (SPT) and IgE mediated allergy, showing immediate reactions after ingestion of small amounts of milk. Twenty-five children also had positive radio allergen sorbent tests (RAST) to cow's milk. Formulae provided consisted of 80% elementary formula in combination with 20% reference or test product. Crossover periods lasted for two weeks. From both products molecular weight (MALDI-TOF method and HPLC) and peptide chain length distribution (adapted Edman degradation) were determined.

RESULTS

Maximum molecular weights of NUT and FAC are 2.1 and 2.56 kDa, respectively. The contribution of free amino acids and small peptides <0.5 kDa is 46% for FAC and 53% for NUT. About 50% of the protein fraction of both products consists of peptides longer than four amino acids. Three children did not complete the study. The other children all tolerated FAC very well; no adverse reactions were reported.

CONCLUSIONS

The new extensively hydrolysed casein-based formula (FAC) can safely be used in children with IgE mediated cow's milk allergy.

Updates in pediatric nutrition

Ongoing research in several areas of pediatric nutrition has new practical applications for community-based pediatricians. For example, a fresh understanding of risk factors for rickets persuades pediatricians to recognize and treat this disease, which was thought to be nearly extinct in the modern industrialized world. Similarly, an expanded awareness of the antibacterial components of breast milk encourages a more complete dialogue between pediatricians and new mothers about the potential benefits of breast-feeding. For those infants with feeding intolerance, new data help to refine the indications for hypoallergenic formulas, which are increasingly recommended for children with a variety of symptoms. The past year also has seen breakthroughs in our understanding of supplemental nutrition for children. Vitamin A may provide direct benefits for the most vulnerable of children, namely premature infants at high risk for lung disease. At the other end of the pediatric spectrum, adolescent athletes seeking to enhance their performance are consuming poorly studied sports supplements that may not be beneficial and may even be toxic. Finally, a greater appreciation for the epidemic of obesity that is sweeping the United States and other countries suggests that children at high risk may represent a far more diverse population than had been recognized previously.