Highly atopic children: formation of IgE antibody to food protein, especially peanut

Perinatal Characteristics and the Sensitization to Cow Milk, Egg Whites and Wheat in Children up to 3 Years of Age

Food sensitization in early life identifies children at risk of developing allergic diseases. We investigated the sensitization to cow milk (CM), egg whites, and wheat. Newborns and infants under 3 years of age with available specific immunoglobulin E (sIgE) data were identified. A retrospective survey was conducted using data from the Chang Gung Research Database. Perinatal characteristics, such as singleton or multiples in a single pregnancy, parity, meconium staining, maternal age, spontaneous delivery or cesarean section, meconium passage, weeks of gestation, birth length, body weight, head and chest circumferences, and season, were obtained. The data on sIgE were collected, and a logistic regression model was used to determine the odds of sensitization. Positive sIgE for CM and egg whites was more likely to occur in boys than in girls. Early-life egg white and wheat sensitization was associated with increased birth body length and weight. A multivariate analysis indicated an association between egg white sIgE positivity and logarithmic total IgE. Higher total IgE levels and younger age were associated with egg white sensitization, and elevated weight and length at birth were linked to food sensitization, particularly to egg whites and wheat.

Feeding a soy formula to children with cow's milk allergy: the development of immunoglobulin E-mediated allergy to soy and peanuts

Peanut allergy has been associated with the intake of soy milk or a soy formula. We studied the development of immunoglobulin E antibodies specific to soy and peanuts and of allergic reactions caused by peanuts, in children with confirmed cow's milk (CM) allergy fed either a soy formula or an extensively hydrolyzed formula (EHF). One hundred and seventy infants with documented CM allergy (CMA) were randomly assigned to receive either a soy formula or an EHF. The children were followed to the age of 4 yr. Peanut-specific immunoglobulin E was measured at the age of 4. A detailed history of the occurrence of allergic reactions caused by peanuts was recorded by the parents. Soy-specific immunoglobulin E antibodies were measured at the time of diagnosis and at the ages of 1, 2 and 4 yr. Immunoglobulin E antibodies to soy (> or =0.35 kU/l) were found in 22 of 70 children fed the soy formula, and in 14 of 70 of the children fed the EHF (p = 0.082). In an open challenge with soy at the age of 4, no immediate reactions were observed. One of 72 children from the soy group had a delayed reaction. immunoglobulin E antibodies to peanuts (> or =0.35 kU/l) were found in 21 of 70 children fed the soy formula and 17 of 69 infants fed the EHF (p = 0.717). The incidence of reported peanut allergy in the soy group was two of 72 (3%) and four of 76 (5%) in the EHF group (p = 0.68). Development of immunoglobulin E-associated allergy to soy and peanuts was rare in our study group of milk allergic children. The use of a soy formula during the first 2 yr of life did not increase the risk of development of peanut-specific immunoglobulin E antibodies or of clinical peanut allergy.

Peanut allergenicity

OBJECTIVE

To provide the reader with a relevant review of the structure and allergenicity of the major peanut allergens, while also exploring predictors of clinical reactivity to peanuts, the natural history of peanut allergy, and novel therapeutic strategies for peanut hypersensitivity.

DATA SOURCES

A PubMed search for the years 1980 to 2004 was performed using the following search terms: peanut allergy, food allergy, anaphylaxis, peanut allergen structure, and peanut immunotherapy.

STUDY SELECTION

Articles highlighting major advances in the study of peanut allergy were selected for further review.

RESULTS

Peanut allergy is the most serious of the hypersensitivity reactions to foods due to its persistence and high risk of severe anaphylaxis. The major peanut allergens and their associated immunodominant IgE-binding epitopes have been characterized. Definition of these allergens has lead to an increased understanding of the peanut-specific immunologic response and improved predictors of clinical reactivity to peanuts. An understanding of these mechanisms is vital for the eventual development of safe and effective immunotherapy for peanut allergic patients. Novel therapeutic and diagnostic approaches are being developed for patients with peanut hypersensitivity.

CONCLUSIONS

Improved understanding of the molecular structure of the major peanut allergens and the peanut-specific immune response has lead to significant diagnostic and therapeutic advances in the study of peanut allergy.

Sensitization to food and airborne allergens in children with atopic dermatitis followed up to 7 years of age

Previously we investigated the eczema prognosis and the risk of developing allergic asthma and rhinitis in a cohort of 94 children with atopic dermatitis. In this second study on the same cohort we address the development of sensitization to foods and airborne allergens, risk factors and, the question whether children with atopic dermatitis who will not become sensitized can be recognized early. Children with atopic dermatitis were followed up regularly from infancy or early childhood to 7 years of age with clinical examination and blood sampling. After age 3, skin prick tests with inhalation allergens were performed yearly. In most children both clinical allergy and sensitization to egg and milk were transient but those to peanut were persistent. Eighty per cent of the children became sensitized to airborne allergens and 75% of them noticed symptoms when exposed. Heredity for atopy and eczema, sensitization to hen's egg, and early onset of eczema entailed an increased risk of becoming sensitized. Children never sensitized had late onset of eczema and less heredity for atopic disease but did not differ in other respects from the sensitized children.

Factors associated with the development of peanut allergy in childhood

BACKGROUND

The prevalence of peanut allergy appears to have increased in recent decades. Other than a family history of peanut allergy and the presence of atopy, there are no known risk factors.

METHODS

We used data from the Avon Longitudinal Study of Parents and Children, a geographically defined cohort study of 13,971 preschool children, to identify those with a convincing history of peanut allergy and the subgroup that reacted to a double-blind peanut challenge. We first prospectively collected data on the whole cohort and then collected detailed information retrospectively by interview from the parents of children with peanut reactions and of children from two groups of controls (a random sample from the cohort and a group of children whose mothers had a history of eczema and who had had eczema themselves in the first six months of life).

RESULTS

Forty-nine children had a history of peanut allergy; peanut allergy was confirmed by peanut challenge in 23 of 36 children tested. There was no evidence of prenatal sensitization from the maternal diet, and peanut-specific IgE was not detectable in the cord blood. Peanut allergy was independently associated with intake of soy milk or soy formula (odds ratio, 2.6; 95 percent confidence interval, 1.3 to 5.2), rash over joints and skin creases (odds ratio, 2.6; 95 percent confidence interval, 1.4 to 5.0), and oozing, crusted rash (odds ratio, 5.2; 95 percent confidence interval, 2.7 to 10.2). Analysis of interview data showed a significant independent relation of peanut allergy with the use of skin preparations containing peanut oil (odds ratio, 6.8; 95 percent confidence interval, 1.4 to 32.9).

CONCLUSIONS

Sensitization to peanut protein may occur in children through the application of peanut oil to inflamed skin. The association with soy protein could arise from cross-sensitization through common epitopes. Confirmation of these risk factors in future studies could lead to new strategies to prevent sensitization in infants who are at risk for subsequent peanut allergy.

Standardization of in vitro methods

IgE-antibody analysis is a major diagnostic procedure and a primary tool in allergological research. The determination of sensitization frequencies and antibody concentrations against allergens of defined sources provides critical information for the estimation of the relative importance of food and environment in clinical allergy. True quantitation is essential and requires assay designs providing allergen excess and mass unit calibration. Standardized and reproducible methods show geographic and culture dependent differences between patient populations and contribute to the quality of diagnosis and treatment of allergic disease.

[Anaphylaxis in children and adolescents: apropos of 44 patients aged 2 months to 15 years]

The increase in frequency of anaphylaxis, an acute allergic reaction which may be fatal, might be explained by the rise in food allergy. We report a cohort of 44 children, aged 2 months to 15.5 years, who were admitted in a pediatric emergency unit for serious allergic events. Thirty-two percent, 86% and 66% presented hypotension, severe edema and respiratory distress, respectively. Three patients were admitted to the ICU. One-fourth of all children had an angioneurotic edema history, 1/3 were asthmatics and 41% had known allergy. Etiologies were: food allergy (42.5%), drugs (14.8%), respiratory allergy (9%), miscellaneous (14.8%), idiopathic (6.4%) and unknown because of incomplete investigations (12.4%). Three-fourths of food allergies were comprised of the expected protein categories (milk, nuts, eggs and fish). Nine children had an allergic relapse during the following months. We otherwise assessed that adrenaline was underused by the medical staff.

Isolation and characterization of proteic allergens in refined peanut oil

Allergic reactions to peanut oil are very much debated, even if the responsibility of peanut oil has been evoked in several cases of adverse reactions, including death related to severe asthma. The aim of the present study was to investigate the presence of allergenic proteins in peanut oil. Proteins were extracted from commercial refined peanut oil, with a relative content in the order of 0.1-0.2 microg per g of oil, and molecular sizes ranging from 14 up to 76kDa in SDS-PAGE. Eight protein bands were systematically observed in crude, neutralized and refined oils, with a molecular mass ranging from approximately 14 to 76 kDa, including one at 18 kDa which was identified by Western blot performed with serum from two allergic patients. The protein extract gave positive IgE-RIA with patient sera, positive in vitro leucocyte histamine release tests and positive skin-prick tests in allergic patients. The allergenic protein was purified by HPLC and [125I] iodide-labelled. It had an isoelectric point at 4.5 in isoelectrofocusing. In conclusion, we have demonstrated the presence of allergenic proteins in crude and refined peanut oil. These proteins are the same size as two allergens previously described in peanut protein extracts.

Cohort study of peanut and tree nut sensitisation by age of 4 years

OBJECTIVE

To determine the prevalence of sensitisation to peanuts and tree nuts in all children born during one year in one geographical area.

DESIGN

Birth cohort study with structured review at ages 1, 2, and 4 years.

SETTING

All children born on the Isle of Wight between January 1989 and February 1990.

SUBJECTS

Of 1456 children originally included, 1218 were reviewed at age 4 years. Of these, 1981 had skin prick tests.

MAIN OUTCOME MEASURES

Positive skin test results, clinical atopic disease, and risk factors for the development of atopy.

RESULTS

15 of 1218 (1.2%) children were sensitised to peanuts or tree nuts (13 to peanuts). Six had had allergic reactions to peanuts (0.5% of the population), one to hazelnuts, and one to cashew nuts; three had had anaphylactic reactions. Seven children had positive skin test results or detectable IgE to peanuts without clinical symptoms. Two children who reacted to peanut in infancy had lost their sensitivity by 4 years. Family history of atopy, allergy to egg (odds ratio 9.9, 95% confidence interval 2.1 to 47.9, and eczema (7.3, 2.1 to 26.1) were important predictors for peanut allergy.

CONCLUSIONS

IgE mediated allergy to peanuts is common in early childhood. In many the allergy persists but a minority may develop tolerance.

Biochemical features of grain legume allergens in humans and animals

Peanuts and soybeans are the major legumes involved in human food allergy, although some data exist on adverse reactions to temperate legumes including pea, green bean, sweet lupin, and lentil. An increasing number of legume proteins or glycoproteins have been characterized as food allergens. Limited data tend to indicate that they are usually different from legume inhalent allergens. Cross-recognition among legume allergens is immunochemically frequent but clinically less common. A common feature to most legume allergens is their natural resistance to thermal, chemical, and in some way, proteolytic denaturation. Finally, other mammals including preruminant calves, and piglets at the time of weaning, are prone to gut immune-mediated reactions to soybean and pea proteins.

Allergy to pistachio: crossreactivity between pistachio nut and other Anacardiaceae

BACKGROUND

Anaphylaxis against Anacardiaceae nuts is uncommon and the allergens involved still poorly characterized. For this reason two patients with allergy towards pistachio nut (a member of the Anacardiaceae family) have been studied.

OBJECTIVE

Identification of immunoallergens present in pistachio nut and analysis of crossreactive antigens in other members of the same plant family, specifically cashew and mango.

METHODS

Presence of specific IgE for pistachio and cashew nut and for mango seed and pulp was determined by skin tests and radioallergosorbent assay (RAST). The allergenic profile of pistachio and cashew was analyzed by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting. Crossreactivity between pistachio and the other Anacardiaceae was studied by RAST inhibition.

RESULTS

Skin tests were positive for pistachio and cashew in the two children and for mango seed in one. RAST was positive for pistachio and cashew in both patients. On immunoblotting, serum from both patients recognized several pistachio and cashew allergens with a molecular weight ranging from < 14.2-70 kDa. RAST inhibition demonstrated common antigenic determinants between pistachio and cashew nut. Crossreactivity was also found between pistachio nut and mango seed but not with mango pulp.

CONCLUSION

Pistachio nut contains several protein allergens able to trigger type I hypersensitivity reactions. These allergens can be found also in cashew nut and mango seed but not in mango pulp.

Purification of allergenic proteins from peanut for preparative of the reactive solid phase of a specific IgE radioimmunoassay

Peanut is one of the most allergenic foods. Detection of specific IgE in the serum of allergic patients requires the purification of allergenic proteins. In the present work, proteins were recovered from peanut kernel after successive treatment in acetone and diethyl ether. The proteins were dissolved in 0.05% TFA and analysed by RP-HPLC with a 0-100% gradient of methanol containing 0.05% TFA. The protein peaks were recovered and tested in SDS-PAGE. Eleven proteins were identified with a M(r) ranging from 13 to 81. Western blotting was performed with sera from allergic patients. Allergenic proteins had a M(r) of 15, 18, 19, 33, 41 and 67. By comparison, a protein fraction from peanut shell contained seven proteins with M(r) ranging from 15 to 81. Only two proteins with M(r) of 18 and 41 were detected in a Western blot. The protein fractions were coupled to epoxy-Sepharose and the gels were used as a solid reactive phase for detection by IgE-RIA of specific IgE from the serum of allergic patients.

Risks of milk formulas containing peanut oil contaminated with peanut allergens in infants with atopic dermatitis

Four cases of infants with atopic dermatitis are reported. In all cases, a sensitization to peanut is demonstrated. Any ingestion of peanuts can be excluded, with the exception of a daily consumption of peanut oil, contained in milk formulas. Oral challenges with peanut oil induce a rash, and elimination of these brands is followed by the disappearance of eczematous lesions. The presence of residual allergenic proteins in peanut oil is thus suspected. Owing to the growing incidence of peanut hypersensitivity, the elimination of peanut oil from all milk formulas, food for babies, and ointments, seems to be highly advisable.

Possible consequences of elimination diets in asymptomatic immediate hypersensitivity to fish

The natural history of IgE antibodies to food without related symptoms is unknown. We have followed the progress of 7 children with various atopic diseases and asymptomatic immediate hypersensitivity to fish, treated with elimination diet in spite of full alimentary tolerance. During the diet period, between 24 and 113 months, all 7 patients presented immediate symptoms upon accidental exposure to or challenge tests with fish (skin symptoms in all 7 cases, digestive in 5, respiratory in 4, and anaphylaxis in 2), which differed from those related to atopic diseases previously present. The levels of fish-specific IgE (prick test, RAST) remained unchanged or were increased. These findings suggest that during elimination diet, and perhaps due to minimal and hidden contact with the allergen, the patients' degree of sensitization may increase, turning an asymptomatic into a symptomatic immediate hypersensitivity.

The influence of diet and environment

I have reviewed a small fraction of the vast literature on the influence of diet, food antigens, and environment on the immune response and would like to emphasize three points. Excess dietary lipid is thought to have a crucial role in inducing obesity and many age-related diseases including cardiovascular disease, malignancy and autoimmune diseases. Micronutrients are involved in protecting the functional integrity of the immune system, particularly to overcome the anti-oxidant deficiency present in refined diet components. Finally, environmental influences such as UV radiation or air pollutants may have an adverse effect in the modification of immune functions when combined with dietary and nutritional factors. It appears that future studies should be directed to understanding the overall interactions of diet and environmental factors, including those of food and viral antigens, and the impact that these have on the maintenance and gene expression of an active and vigorous immune system in healthy and diseased states.