Determination of allergenicity to three cow''s milk hydrolysates and an amino acid‐derived formula in children with cow''s milk allergy

BACKGROUND: Products based on hydrolysed cow milk proteins or amino acid mixtures are recommended in children with cow's milk hypersensitivity. However, some children who are allergic to cow's milk and who clinically react to substitute milk formulas have been observed. OBJECTIVE: To determine the tolerance and allergenicity of protein hydrolysate or amino acid-derived formulas in children with IgE-mediated cow's milk allergy. METHODS: Twenty children with positive cow's milk challenges, positive skin prick tests and/or serum-specific IgE antibodies to cow's milk were selected. Oral challenges, skin prick tests and serum-specific IgE antibodies to extensively hydrolysed whey formula, partially hydrolysed whey formula, extensively hydrolysed casein formula and amino acid-derived formula were performed. RESULTS: Five out of 17 (5/17) children reacted to partially hydrolysed whey formula, (3/16) to extensively hydrolysed whey formula, (2/10) to amino acid-derived formula, (1/16) to extensively hydrolysed casein formula. Only extensively hydrolysed casein formula was tolerated by at least 90% (with 95% confidence intervals) of children. Hydrolysates provoked early and delayed clinical reactions, amino acid mixtures only delayed reactions. Partially hydrolysed whey formula elicited a significantly higher number of positive skin prick test reactions than other formulas. Two children had specific IgE antibodies to extensively hydrolysed whey formula, one to partially hydrolysed whey formula, one to extensively hydrolysed casein formula and none to amino acid-derived formula. CONCLUSION: In this study, none of the cow's milk substitutes has been found to be non-allergenic. Our results suggest that in children with IgE-mediated cow's milk allergy, the first ingestions of extensively hydrolysed cow's milk protein formulas require strict medical supervision because of immediate reactions. This is not the case for amino acid-derived formula. Moreover, our data suggest that treatment of children allergic to cow's milk with cow's milk substitutes should be monitored for several days to document tolerance.     

A hydrolysed rice-based formula is tolerated by children with cow''s milk allergy: a multi-centre study

BACKGROUND: Children allergic to cow's milk are fed a soy- or a hydrolysed cow's milk-based substitute. Neither can rule out a sensitization risk. Previous studies have shown that hydrolysed rice is tolerated by animals and children with multiple food hypersensitivities. OBJECTIVE: A prospective clinical assessment of tolerance to a rice-based hydrolysed formula was carried out in children allergic to cow's milk. Patients and methods One hundred children (42 girls and 58 boys, mean age 3.17+/-2.93 years, median 2.20, range 0.18-14.6 years) with a history of immediate reactions to cow's milk and confirmed at double-blind, placebo-controlled food challenge (DBPCFC) when not contraindicated were assessed for clinical tolerance to cow's milk proteins. Their allergy work-up included skin prick tests with whole milk, alpha-lactalbumin (ALA), beta-lactoglobulin (BLG) and total caseins, and specific IgE determinations using CAP technology were performed against whole milk, ALA, BLG and casein. Sensitization to rice and rice-based hydrolysed formula was similarly investigated. Patients' sera were evaluated at immunoblotting for specific IgE to cow's milk proteins, rice and rice-based hydrolysed formula. DBPCFC was carried out with increasing doses of a rice-based hydrolysed formula. RESULTS: All patients were sensitized to cow's milk and/or at least one cow's milk protein fraction. Eighty-seven out of 99 were positive to cow's milk and/or a cow's milk protein fraction at skin prick test. Positive (>0.35 kUA/L) specific IgE determinations were found for cow's milk and/or milk fractions (92/95), rice (21/91) and hydrolysed rice infant formula (4/91). At immunoblotting, sera from 96 children were positive to alpha-casein (n=54), beta-casein (n=38), ALA (n=57), BLG (n=37) and bovine serum albumin (n=61). Similarly, although patients' sera often contained specific IgE against rice proteins at CAP (21/91) and immunoblotting (70/96), only six very weakly positive responses were observed against rice-based hydrolysed formula. All DBPCFC with rice-based hydrolysed formula were negative. CONCLUSIONS: Rice-based hydrolysed formula is a possible alternative not only for children with multiple allergies, but also for children with cow's milk allergy.     

The efficacy of amino acid-based formulas in relieving the symptoms of cow''s milk allergy: a systematic review

The aim of this systematic review was to evaluate the efficacy of amino acid-based formulas (AAF) in patients with cow's milk allergy (CMA). Studies were identified using electronic databases and bibliography searches. Subjects eligible for inclusion were patients of any age with CMA or symptoms suggestive of it. Comparisons of interest were AAF vs. extensively hydrolysed formula (eHF), AAF vs. soy-based formula (SF) and AAF vs. cow's milk or cow's milk-based formula. Outcomes of interest were gastrointestinal (GI), dermatological, respiratory and behavioural symptoms as well as growth. A total of 20 studies [three head-to-head randomized controlled trials (RCTs), three cross-over challenge RCTs, seven clinical trials (CTs) and seven case reports (CRs)] were included in the review. In infants with confirmed or suspected CMA, the use of an AAF was shown to be safe and efficacious. Findings from RCT comparisons of AAF with eHF showed that both formulas are equally efficacious at relieving the symptoms of CMA in confirmed or suspected cases. However, infants in specific subgroups (e.g. non-IgE mediated food-induced gastro-enterocolitis-proctitis syndromes with failure to thrive, severe atopic eczema, or with symptoms during exclusive breastfeeding) were more likely overall to benefit from AAF, as intolerance to eHF may occur. In such cases, symptoms persisting despite eHF feeding usually remit on AAF, and catch-up growth may be seen. Meta-analysis of the findings was not possible due to lack of homogenous reporting of outcomes in the original trials. This systematic review shows clinical benefit from use of AAF in both symptoms and growth in infants and children with CMA who fail to tolerate eHF. Further studies are required to determine the relative medical or economic value of initial treatment with AAF in infants at high risk of eHF intolerance.     

A case of allergy to cow's milk hydrolysate

We here report a girl, now 3 years old, who has suffered from severe food allergy since her first year of life. She was strongly allergic to cow's milk, and had high levels of IgE antibody (AB) to casein (210 kU/I), beta-lactoglobulin (43 kU/I), and alpha-lactalbumin (23 kU/l) at 12 months of age. In addition, at the same age, she showed positive (2-4+) skin prick reactions to both unboiled and boiled formulas (Profylac, Nutramigen, and Neocate), besides being positive in RAST to Nutramigen (0.6 kU/l). During the first 3 years, IgE Ab levels against casein and Nutramigen increased to 310 and 1.6 kU/l, respectively. Furthermore, at 3 years of age, she had positive RAST to 14 of 15 tested food allergens, being negative only to codfish. Assessment of eosinophil-related markers revealed high total eosinophil count, increased eosinophil activity, and a low ratio of interferon (IFN)-gamma:IL-5, indicating enhanced IL-5 production. The food allergy was correlated to poor weight gain and increasing problems with atopic allergy in the airways.     

Immunoglobulin E and immunoglobulin G4 antibodies to cow''s milk in children with cow''s milk allergy

The presence of cow's milk specific antibodies of immunoglobulin E and G4 classes were studied in 47 children with a positive clinical history of cow's milk allergy. The children were challenged with cow's milk orally. The clinical diagnosis was verified by immediate reactions in 25 patients while 22 had late reactions or were provocation test negative in spite of the clinical history. There was no relation between levels of cow's milk specific IgG4 antibodies and provocation test result, i.e. neither with immediate or late reactions. Total IgF. Was elevated above + 1 SD for age in 31 41 tested patients. Of these, 29 had immediate type reactions to cow's milk wheat flour and/or egg white, while only two of 10 children with IgE of less than +1 SD had a demonstrable allergy to any of these foods. The sensitivity was 80%. Specific IgE antibodies to cow's milk were demonstrated in 11 of 14 children with immediate reactions and in three of 15 who were provocation test negative or had only late reactions. This means a sensitivity of 79% and a specificity of 80%. At least had only late reactions. This means a sensitivity of 79% and a specificity of 80%. At least one of the four patients with specific IgE but negative provocation test result had earlier shown an immediate reaction when challenged with cow's milk indicating that the specific IgE antibodies were not truly "false" positive reactions but a consequence of previous allergy. Our results confirm an association between elevated total serum IgE and food allergy and an association between positive RAST to cow's milk and positive provocations in young children. We did not find any evidence for specific IgE-1 antibodies playing a role in these patients.     

Cow's milk protein-specific IgE concentrations in two age groups of milk-allergic children and in children achieving clinical tolerance

BACKGROUND: IgE-mediated cow's milk protein allergy (CMPA) is usually outgrown in children by the age of 3 years. The immunological responses to cow's milk proteins in children who achieve tolerance, in comparison with those who remain allergic, however, are not well described. OBJECTIVE: To compare the level of cow's milk protein-specific IgE among children with documented CMPA under the age of 3 years, another group over the age of 9 years (persistent allergy), and in another group of children in whom clinical tolerance developed. METHODS: Stored sera from children with CMPA were analysed for IgE antibodies specific for whole cow's milk, casein, whey, alpha-lactalbumin (ALA), beta-lactoglobulin (BLG), and bovine serum albumin (BSA) using the Pharmacia CAP System FEIA. RESULTS: Within each group of CMPA children, the concentration of specific IgE antibody to casein proteins was not significantly different from that to whey proteins. However, children in the group with CMPA over 9 years of age had significantly greater concentrations of whole milk (P = 0.02) and casein-specific (P = 0. 04) IgE antibodies compared with the group of children with CMPA under age 3 years. Children under the age of 3 years had a higher median concentration of casein-specific IgE (20.2 vs. 5.5, P = 0.04) than another group of 11 children (mean age 3.5 years), who later lost their milk allergy. Out of 16 children who lost sensitivity to milk, 75% had milk-specific IgE levels below 14.3 kUA/L (median, 1.3 kUA/L). CONCLUSIONS: Although a dominant allergenic milk protein fraction was not identified within either of the two age groups, those with persistent CMPA over age 9 years had significantly elevated levels of milk and casein-specific IgE compared with younger children with CMPA.     

Infant feeding patterns affect the subsequent immunological features in cow''s milk allergy

BACKGROUND: The first exposure to food antigens provokes an immune reaction in an infant, its type depending on the quantity and frequency of doses and the age at introduction, and also being influenced by genetic factors. Most infants develop tolerance to food antigens, but in a small minority they provoke adverse symptoms. OBJECTIVE: To study the effects of breast and formula feeding and other environmental and genetic factors on the subsequent type of cow's milk allergy classified by the presence or absence of immunoglobulin (Ig) E antibodies to cow's milk. METHODS: A cohort of 6209 infants was followed prospectively from birth for symptoms of cow's milk allergy. The infant-feeding regimen was recorded at the maternity hospital and at home. At a mean age of 6.7 months, a total of 118 infants (1.9%) reacted adversely to a challenge with cow's milk. Before the challenge, the response to a skin-prick test with cow's milk and serum IgE cow's milk antibodies was measured. RESULTS: At challenge, 75 (64%) infants showed IgE-positive reactions to cow's milk, their most common symptom being acute-onset urticaria. Significant risk factors for the presence of IgE cow's milk antibodies in allergic infants were long breast-feeding (odds ratio [OR] 3.9, 95% confidence interval [CI] 1.6-9.8), exposure to cow's milk at the maternity hospital (OR 3.5, 95% CI 1.2-10.1) and breast-feeding during the first 2 months at home either exclusively (OR 5.1, 95% CI 1.6-16.4) or combined with infrequent exposure to small amounts of cow's milk (OR 5.7, 95% CI 1.5-21.6). Fifty infants had their first adverse symptoms during exclusive breast-feeding, and 32 infants were sensitized during exclusive breast-feeding. Most of the infants in both cases were IgE-positive: 37 and 23, respectively. CONCLUSIONS: In infants who are prone to developing cow's milk allergy, prolonged breast-feeding exclusively or combined with infrequent exposure to small amounts of cow's milk during the first 2 months of life induces development of IgE-mediated response to cow's milk.     

Concurrent cereal allergy in children with cow''s milk allergy manifested with atopic dermatitis

BACKGROUND: There is increasing consensus about the significance of food allergens in the pathogenesis of atopic dermatitis (AD) in infancy and childhood, with cow's milk and egg accounting for most of the reactions. Previous studies have indicated that multiple food sensitization, such as cereals, is very common in patients with cow's milk allergy (CMA). Evidence is lacking, however, as to its clinical relevance. OBJECTIVE: The purpose of this study was to determine the concurrent occurrence of cereal allergy among children with challenge-proven CMA who have residual symptoms, such as AD and/or gastrointestinal symptoms, during cow's milk elimination diet. Further, we sought to evaluate the utility of patch testing in prescreening foods other than cow's milk behind allergic symptoms in children. METHODS: The study population comprised 90 children, aged from 2.5 to 36 months (mean 1.1 years), with challenge-proven CMA. As a result of residual symptoms during meticulous cow's milk elimination diet (AD: n=80, and gastrointestinal: n=10), the children were put on a cereal elimination diet (oats, wheat, rye, and barley) and skin prick tests (SPT) and patch testing with cereals were performed. Open cereal challenge was performed to confirm cereal allergy. RESULTS: Cereal challenge was positive in 66 (73%) of the children with CMA. Of them, 17% reacted with immediate reactions and delayed-onset reactions were seen in 83% of the children. SPT was positive in 23%, patch test in 67%, and either SPT or patch test was positive in 73% of the children with cereal allergy. SPT gave the best positive predictive value, whereas SPT together with patch test gave the best negative predictive value. CONCLUSIONS: Residual symptoms, such as eczema or gastrointestinal symptoms in CMA children may be a sign of undetected allergy to other food antigens. SPT with cereals aids in diagnosing cereal allergy in small children, especially when used together with patch testing.     

Placebo reactions in double-blind, placebo-controlled food challenges in children

BACKGROUND: A cardinal feature of the double-blind, placebo-controlled food challenge (DBPCFC) is that placebo administration is included as a control. To date, the occurrence and diagnostic significance of placebo events have not extensively been documented. OBJECTIVE: To analyse the occurrence and features of placebo events in DBPCFCs and to assess their contribution to the diagnostic accuracy of the DBPCFC in children. METHODS: The study population consisted of 132 challenges in 105 sensitized children (age range 0.7-16.6 years, median 5.3 years), who underwent DBPCFCs with cow's milk, egg, peanut, hazelnut and soy. Placebo and active food challenges were performed on different days. RESULTS: A total number of 17 (12.9%) positive placebo events occurred, which could be classified as immediate (9/17), late-onset (8/17), objective (11/17) or subjective (6/17). Four of 74 (5.4%) positive active food challenges were revealed to be false positive by administration of a placebo challenge. This is 3% (4/132) of all challenges. When computed by a statistical model, the false positive rate was 0.129 (12.9% of all challenges). CONCLUSION: Placebo events with diverse clinical characteristics occur in DBPCFCs in a significant number of children. The diagnostic significance of the administration of a placebo challenge is first, to identify false positive diagnoses in DBPCFCs by refuting false positive tests in individual patients. Secondly, to allow for blinding of the active food challenge. Thirdly, applying a statistical model demonstrates that some positive challenges may be false positive and that the test may need to be repeated in selected cases.     

Defective tumour necrosis factor-alpha production in mother''s milk is related to cow''s milk allergy in suckling infants

BACKGROUND: The precise role of leucocytes in human milk is still unresolved. OBJECTIVE: To assist in clarifying the immune mechanisms involved in the development of CMA in suckling infants, we studied the role of immunoregulatory leucocytes and their mediators in human breast milk. METHODS: The study population consisted of 43 lactating mothers and their infants, aged 0.25-8.0 months, followed-up prospectively from birth. Of these mothers, 27 had an infant with challenge-proven cow's milk allergy manifested with either skin (n = 23), gastrointestinal (n = 2) or skin and gastrointestinal symptoms (n = 3). Sixteen mothers with a healthy infant served as controls. We evaluated the spontaneous and mitogen-induced tumour necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) production of human milk leucocytes and isolated peripheral blood lymphocytes in vitro with a commercial ELISA kit. RESULTS: TNFalpha production of breast milk leucocytes was significantly lower in the mothers with a cow's milk-allergic infant, whereas IFNgamma production of these cells was comparable in the two groups. CONCLUSION: Our results suggest that in the breast milk of mothers having an infant with cow's milk allergy, the number and function of TNFalpha-producing cells is defective. This might lead to a disturbance in the development of oral tolerance and thereby to the development of CMA in suckling infants. These novel results may help in clarifying the etiopathogenesis of CMA.     

Does severity of low‐dose,double‐blind,placebo‐controlled food challenges reflect severity of allergic reactions to peanut in the community?

BACKGROUND: The severity of allergic reactions to food appears to be affected by many interacting factors. It is uncertain whether challenge-based reactions reflect the severity of past reactions or can predict future risk. OBJECTIVE: To explore the relationship of a subject's clinical history of past reactions to the severity of reaction elicited by a low-dose, double-blind, placebo-controlled food challenge (DBPCFC) with peanut. METHOD: Cross-sectional questionnaire assessment of community-based allergic reactions and low-dose DBPCFC in self-selected peanut-allergic subjects. Reaction severity was assessed using a novel scoring system, taking account of the dose of allergen ingested. RESULTS: Forty subjects (15 males, 23 children, 23 asthmatics by history) were studied. Only the most recent community reaction predicted the severity of reaction in the DBPCFC, but even this association was weak (r=0.37, P=0.03). Peanut-specific IgE (PsIgE) and skin prick test (SPT) weal size were not associated with community score but PsIgE level correlated well with the challenge score (r=0.6, P=0.001). Asthma did not affect the eliciting dose or challenge score directly but the association of PsIgE and challenge score was stronger in those without asthma (r=0.72, P=0.001) than in those with asthma (r=0.48, P=0.02). CONCLUSIONS: The scoring system developed appears to improve the sensitivity of assessment of reactions induced by DBPCFC. This is the first prospective study showing an association between PsIgE levels and clinical reactivity in DBPCFC, an effect that is more pronounced in non-asthmatics. This finding has important implications for the clinical care of subjects with food allergy. There is a poor correlation between the severity of reported reactions in the community and the severity of reaction elicited during low-dose DBPCFC with peanut.     

Effect of ingestion of cow''s milk hydrolysed formulas on whey protein-specific Th2 immune responses in naïve and sensitized mice

Background For genetically predisposed atopic infants, cow's milk protein hydrolysed formulas have been widely used. Objective Whether hydrolysed formulas can induce oral tolerance to whey proteins will be extensively studied in naïve and sensitized mice. Methods Antigenicity of hydrolysed formulas was first studied using immunoblotting. Naïve mice fed hydrolysed formulas for 1–4 weeks were sensitized with whey allergens. In contrast, mice sensitized with whey allergens were fed hydrolysed formulas continually for 12 weeks. Results Whey allergens were found in Nan and Neoangelac FL. Large whey peptides with antigenicity were found in Nan‐HA. Profound suppression of IgE, IgG1 and IgG responses to whey allergens were induced in those fed Nan for 1 week, or Nan‐HA for 4 weeks. IgE responses to whey allergens were suppressed in those fed Neoangelac FL for 4 weeks, or Nan‐HA for 1–2 weeks. In contrast, those fed extensively hydrolysed formulas for 1–4 weeks failed to show decreased responses. On the other hand, IgE responses to β‐lactoglobulin, but not to bovine serum albumin or α‐lactalbumin, were decreased in sensitized mice fed Nan for 12 weeks. There was no suppression in sensitized mice fed hydrolysed formulas. Conclusion Suppression of IgE responses to whey proteins was readily induced in naïve mice fed Nan or Nan‐HA for 1 week. In contrast, it was hardly induced in sensitized mice even after prolonged feeding of Nan for 12 weeks, let alone hydrolysed formulas.     

Ready-to-use introduction schedules for first exposure to allergenic foods in children at home

Background:  The vast majority of children will undergo their first exposure to common allergenic foods at home. However, the first exposure may lead to clinical reactions. It has been proposed to introduce allergenic foods gradually into the diets of children at risk for food allergy, but no practical dietary advice has been devised.
Objective:  The aim of this study was to devise safe introduction schedules for common allergenic foods for use at home, based on the challenge doses as administered in double-blind, placebo-controlled food challenge (DBPCFCs) in children who were never exposed previously to these foods.
Methods:  Seventy-two DBPCFCs were performed in 63 children as a first known exposure. The incrementing challenge doses were converted into equivalent portions of these foods in their usual household form and incorporated in introduction schedules. The feasibility of the introduction scales was tested in parents of the children attending our clinic.
Results:  Based on the results of the positive challenges (37) in which severe reactions did not occur, detailed introduction schedules and a reference photograph of the required increasing amounts of food were devised for use at home. Feasibility testing showed that, when using these introduction schedules, parents portioned the initial doses significantly lower than without detailed instructions.
Conclusions:  The introduction schedules and reference photograph provide information for parents to introduce the required amounts of allergenic foods in initial low doses at home. This is expected to improve the safety of this procedure.     

Cow's milk allergy: diagnostic accuracy of skin prick and patch tests and specific IgE

BACKGROUND: The objective of the present study was to evaluate the relevance of skin tests and the concentration of cow's milk-specific IgE antibodies in correlation with oral cow's milk challenge in infants with suspected cow's milk allergy. METHODS: The study material comprised 143 infants under the age of 2 years who had undergone a diagnostic elimination challenge because of suspected cow's milk allergy in 1996. Cow's milk-specific IgE was measured, and skin prick and patch tests were performed. RESULTS: Of the 143 oral cow's milk challenges performed, 72 (50%) were positive. Of the positive reactions, 22 involved immediate-type reactions. In 50 patients, delayed-onset reactions of eczematous or gastrointestinal type appeared. Of the infants with challenge-proven cow's milk allergy, 26% showed elevated IgE concentrations to cow's milk, 14% had a positive skin prick test, and 44% had a positive patch test for cow's milk. Interestingly, in most patch test-positive patients, the prick test for cow's milk was negative. CONCLUSIONS: Our study demonstrated that many patients with a negative prick test result had a positive patch test to cow's milk. The patch test was a more sensitive method than the prick test or RAST to detect cow's milk allergy in this study population. Our results indicate that patch testing will significantly increase the probability of early detection of cow's milk allergy. Confirmation of the diagnosis is essential in patients with negative test results but a clinical suspicion of food allergy, and in patch test-positive patients. For this purpose, the most reliable method is the elimination-challenge procedure.     

A protocol for oral desensitization in children with IgE-mediated cow's milk allergy

OBJECTIVES: To desensitize children with severe immunoglobulin (Ig)E-mediated cow's milk allergy in a period of 6 months by introducing increasing daily doses of cow's milk (CM) in order to enable the child to assume 200 ml of CM daily, or to induce tolerance of the highest possible CM dose. STUDY DESIGN: Twenty-one children at least 6 years old with severe IgE-mediated CM allergy were admitted to the study. A convincing history of IgE-mediated CM allergy or a positive double-blind placebo-controlled food challenge with CM confirmed the diagnosis. Oral desensitization was performed with increasing doses starting from 0.06 mg of CM proteins. RESULTS: Overall, 15 of 21 children (71.4%) achieved the daily intake of 200 ml during a 6-month period; three of 21 children (14.3%) tolerated 40-80 ml/day of undiluted CM; three of 21 children (14.3%) failed the desensitization because they presented allergic symptoms after ingesting minimal amounts of diluted CM. Conclusions: We successfully desensitized 15 of 21 children with severe IgE-mediated CM allergy in a period of 6 months. We stress the importance of the partial outcome in those three of 21 children who could not reach the maximum amount of 200 ml/day of whole CM, but were able to tolerate 40-80 ml/day of CM. In this way we dramatically reduced the risk of severe reactions after accidental or unnoticed introduction of low quantities of CM. We do not propose generalizing this method beyond trained staff.     

Use of immunoblotting and monoclonal antibodies to evaluate the residual antigenic activity of milk protein hydrolysed formulae

Background Partial and extensive hydrolysed protein formulae have been developed to lower or eliminate the antigenicity of milk proteins. Although normally well tolerated, extensive hydrolysutes have been reported to induce serious allergic reactions in very sensitive children. Moreover, clinical praetice has often raised concern about the role of partial hydrolysates in cow's milk allergy prevention. Objective Starting from these considerations, we used anti-casein monoclonal antibodies to evaluate the presence of residual antigenic activity in both partially and extensively protein hydrolysates. Methods Electrophoretic analyses associated with immunoblotting technique were performed using nine protein-enriched commercial formulae. Results The presence of different amounts of residual intact cow's milk proteins and/or polypeptidic material with conserved antigenic activity (according to the extensive or partial hydrolysis) was verified in most milk-based samples considered. Conclusion The use of monoclonal antibodies and immunoblotting could be useful for the quality control of commercial hypoaliergenic' formulae.     

Evaluation by SDS-PAGE and immunoblotting of residual antigenicity in hydrolysed protein formulas

Background Extensively hydrolysed protein formulas are widely used as an alternative diet for children with cow's milk allergy. Partially hydrolysed protein formulas have been noted in some studies as useful in the prevention of allergy in infants at high risk of atopy. Although normally well tolerated, these ‘hypoallergenic’ products have been reported to cause serious immunological reactions in very sensitive subjects. Objective Starting from these considerations, we studied some commercial hydrolysed formulas in search of biological data supporting the observed clinical reactions. Methods We set up an electrophoretic method sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) which allowed us to study the molecular weight of peptides contained in hydrolysed products. Then, using the immunoblotting technique we evaluated the reactivity of circulating IgE (from serum of children allergic to cow's milk proteins) with the residual intact proteins and with the peptides present in these formulas. Results Both group of milk proteins (caseins and whey proteins) were important allergens for children included in this study. The presence of high-molecular polypeptides was shown in partial hydrolysed formulas as such and in extensive hydrolysed products after protein enrichment by trichloroacetic acid (TCA) precipitation. Intact residual proteins were mainly responsible for the formation of FgE-antigen complexes observed in immunoblotting. More rarely, polypeptides of partial hydrolysed formulas were involved in immunological responses. Conclusions Both partial and extensive hydrolysed formulas could induce clinical reactions in very sensitive subjects. These responses are mainly associated with allergy to the small amounts of residual intact proteins.     

Prevalence and Clinical Impact of IgE-Mediated Food Allergy in School Children With Asthma: A Double-Blind Placebo-Controlled Food Challenge Study

Purpose

Recent studies indirectly suggest a possible link between food allergy (FA) and asthma. Most of them have evaluated the occurrence of FA in asthmatic children, especially in the first year of life, using questionnaire-based studies or specific IgE (sIgE) assay. The aim of this study was to evaluate the prevalence and clinical impact of IgE-mediated FA in school children with asthma using a double-blind placebo-controlled food challenge (DBPCFC).

Methods

The study group consisted of school children with atopic asthma who were admitted to the Department of Pediatric Allergology, Gastroenterology and Nutrition, Medical University of Lodz, for the evaluation of food hypersensitivity. The diagnosis of FA was established using questionnaires, sIgE analysis, and the DBPCFC. Asthma severity and asthma control state were also assessed.

Results

A relationship between consumed food and complaints was reported in 180 children (49.7%). Seventy children (19.3%) were sensitized to food allergens. IgE-mediated FA was confirmed in 24 children (6.6%), while 11 children (3%) demonstrated respiratory symptoms. Food-induced asthma exacerbations were observed in 9 patients (2.5%). Statistically significant differences in the prevalence of atopic dermatitis (P<0.002), urticaria (P<0.03), digestive symptoms (P<0.03), rhinitis (P<0.02), sIgE level (P<0.001), positive family history of atopy (P<0.001) and FA in history (P<0.001) were found between asthmatic children with FA and those without. Children with food-induced asthma exacerbations demonstrated significantly greater severity, poorer controls, and worse morbidity compared to those without.

Conclusions

Although food-induced respiratory reactions in children with asthma were rare, they were classified as severe and associated with worse morbidity, greater severity, and poorer control. As the most commonly observed symptoms were coughing and rhinitis, which can be easily misdiagnosed, a proper diagnosis is essential for improving the management of both clinical conditions.     

Pitfalls in double-blind, placebo-controlled oral food challenges

Although controlled oral food challenges are considered to be the gold-standard in the diagnosis of food related symptoms, especially if performed in a double-blind, placebo-controlled food challenges (DBPCFC) manner, there are still many unanswered questions and newer aspects, which may explain some pitfalls encountered during oral food challenges. For stopping an oral food challenge and declaring a challenge as positive or negative, symptoms should be objective and/or repetitive. The time interval between administering the food and observing the clinical reaction is an ambivalent factor. Possible reasons for false negative assessments include inadvertent drug use during oral challenges, and the fact that a short-term specific oral tolerance induction (SOTI) may be induced as increasing amounts of the offended food are administered during a titrated oral food challenge. Possible reasons for false positive assessments are the difficulty to maintain an appropriate strict diet throughout the oral challenge procedure, and that the elimination diet implemented before the oral food challenge in children with atopic eczema and suspected food related symptoms may itself be responsible for immediate type clinical symptoms, which had not been reported by the parents before. Finally augmentation factors are among the most plausible explanations for the inadequate reproducibility of an oral food challenge. Although a 100% standardization of the challenge procedure does not seem realistic, efforts should be made to improve the methodology used so far. On the contrary, the possible relation of DBPCFC and SOTI may offer potential advantages for future therapeutic approaches of food allergy.