Peanut IgE Research Articles

Growth Characteristics Of Children Aged 2-17 Years With Food Allergy

Children with food allergy may have limitations in diet and intake that impact growth. Research at this time has focused on cohorts of children with documented food allergy to characterize nutritional status and growth parameters, but population wide investigations are lacking. Nationally representative data from The National Health and Nutrition Examination Survey (NHANES) 2005-2006 were used to analyze anthropometric measurements in 2911 children aged 2-17. Height, weight and BMI for age were calculated using EpiInfo (CDC). Differences in these measures between those with and without likely food allergy (defined as milk, egg or peanut IgE above the 95% PPV) were analyzed by linear and logistic regression, adjusting for age, gender, race/ethnicity and family income. 1% of children had IgE levels highly suggestive of food allergy (0.03% milk, 0.3% egg and 0.8% peanut). The mean BMI percentile for these children was 10.8% less than for the general population (95% CI: 0.8-20.9% p= 0.04). 15% of those with likely food allergy had a BMI percentile ≤ 10th percentile, compared to 6% of those without likely food allergy (adjusted OR: 2.76, 95% 1.10- 6.90: p=0.03). However, height for age percentile was not lower for this group (p=0.99) and there were not significant differences in plasma levels of total or HDL cholesterol (p=0.95 and 0.29, respectively), or vitamin D (p=0.89). Children with likely food allergy have lower BMI than the general population, but height appears to be unaffected. Whether these children have more subtle nutritional deficiencies should be investigated.

Clinical utility of thresholds versus CRD

Since food challenge is time consuming and not always without a risk for the patient, surrogate parameters have been introduced. Among the best studied are case history, size of Skin Prick Test and the level of specific IgE towards a food allergen. In the later case, decision points (ie. the level of specific IgE above which there would be a 95 % probability of the patient being challenge positive) have been introduced for various foods, including, egg, milk, nuts and peanuts. Two major problems arise, however, from such an approach. Firstly, the decision point may vary considerably between centres. This has been shown for hen’s egg, where different centres have published decision points varying from >0,35 to above 14 kIU/l. Secondly, in many cases, cross reacting antibodies may limit the validity of the decision point. An example is seen in peanut allergy, where a level above 10 kIU/l is considered positive in most published papers; but higher levels of peanut IgE are often detected in pollen allergic patients with high levels of IgE towards grass and birch. Most foods contain several allergenic proteins, with varying clinical relevance. Peanut contain several allergens, of which some are clinically irrelevant but important due to cross reaction with IgE against pollen whereas others, especially the protein ara H2, are directly correlated the clinical disease. Component resolved diagnostics (CRD) may thus present a major step forward in the search for surrogate parameters. The ideal surrogate parameter should be able to discriminate between positive and negative challenge and also to correlate to disease severity and clinical sensitivity (threshold). Threshold is an important parameter to establish both in the single patient, facilitating tailor made guidelines for the patient, and in the community. Measurement of specific to CRD’s would hopefully result in a better correlation to threshold than conventional techniques, but this idea remains yet to be proven. In the peanut example above, although a very nice decision point for ara H2 was established, less convincing correlations to clinical threshold in the patient population was found.

Effect of Instant Controlled Pressure Drop on IgE Antibody Reactivity to Peanut, Lentil, Chickpea and Soybean Proteins

Background: The use of legume seeds is being expanded in the food industry due to their excellent nutritional and technological properties. However, legumes have been considered causative agents of allergic reactions through ingestion. Previous studies indicated that processing methods combining heat and steam pressure, such as instant controlled pressure drop (DIC®), could decrease allergenicity. The aim of this study was to investigate the impact of DIC treatment on peanut, lentil, chickpea and soybean IgE antibody reactivity. Methods: Peanut, lentil, chickpea and soybeanseeds were subjected to DIC treatment at different pressure and time conditions (3 and 6 bar for 1 and 3 min). Control (raw) and DIC-treated extracts were analyzed by SDS-PAGE and immunoblotting using a serum pool from sensitized patients. Results: DIC treatment did not affect the total protein content of legume seeds. Nevertheless, modifications of protein profiles after DIC showed a general decrease in IgE binding to legume proteins that was correlated to a higher steam pressure and longer treatment. The immunoreactivity of soybean proteins was almost abolished with treatment at 6 bar for 3 min. Conclusions: The results demonstrated that DIC treatment produces a reduction in the overall in vitro IgE binding of peanut, lentil and chickpea and a drastic reduction in soybean immunoreactivity.

Efficacy and safety of high‐dose peanut oral immunotherapy with factors predicting outcome

Peanut allergy is severe and rarely resolves. To test the efficacy and safety of a new oral immunotherapy (OIT) protocol for peanut allergy. Twenty-two peanut-allergic children underwent oral challenge. OIT was administered by gradual updosing with 2-weekly increments (8-38 weeks) to 800 mg of protein (5 peanuts/day) followed by 30-week maintenance. Oral challenge was repeated after 6 and 30 weeks maintenance. Twenty-two children (median 11 years) had positive challenges (threshold 1-110 mg). Nineteen of 22 (86%) tolerated updosing and maintenance at 800 mg protein/day. One of 22 dropped out; 2/22 tolerated updosing and maintenance at 200-400 mg protein. Reactions, mostly mild, occurred in 86% during immunotherapy, adrenaline was not required. Eight of 8 with pre-immunotherapy peanut IgE<27.3 kU/L required no dose adjustment compared with 5/13 with pre-immunotherapy peanut IgE≥27.3 kU/L. Twelve of 22 (54%) required a transient dose reduction because of reactions possibly related to extrinsic factors: tiredness, infection and exercise. After 6 weeks, 12/22 (54%) had no reaction to a 2.6 g protein challenge. After 30 weeks, 14/22 (64%) tolerated 6.6 g protein. The median tolerated peanut dose increased 1000-fold following immunotherapy, from 6 to 6459 mg of protein. We used a novel protocol using gradual updosing, and higher maintenance dose resulting in a better outcome compared with rush protocols. There was a 1000-fold increase in the amount of peanut tolerated with a good safety profile. No serious adverse events occurred. Most subjects tolerated five peanuts and all were protected against amounts likely during accidental ingestion. New information is provided on 'extrinsic factors', updosing method and factors associated with success (trial registration http://ClinicalTrials.gov- ID number NCT01259804).

Maternal consumption of peanut during pregnancy is associated with peanut sensitization in atopic infants

Peanut allergy is typically severe, lifelong, and prevalent. To identify factors associated with peanut sensitization. We evaluated 503 infants 3 to 15 months of age (mean, 9.4 months) with likely milk or egg allergy but no previous diagnosis of peanut allergy. Atotal of 308 had experienced an immediate allergic reaction to cow's milk and/or egg, and 204 had moderate to severe atopic dermatitis and a positive allergy test to milk and/or egg. Apeanut IgE level ≥5 kU(A)/L was considered likely indicative of peanut allergy. A total of 140 (27.8%) infants had peanut IgE levels ≥5 kU(A)/L. Multivariate analysis including clinical, laboratory, and demographic variables showed frequent peanut consumption during pregnancy (odds ratio, 2.9; 95% CI, 1.7-4.9; P< .001), IgE levels to milk (P= .001) and egg (P< .001), male sex (P=.02), and nonwhite race (P= .02) to be the primary factors associated with peanut IgE ≥5 kUA/L. Frequency of peanut consumption during pregnancy and breast-feeding showed a dose-response association with peanut IgE ≥5 kU(A)/L, but only consumption during pregnancy was a significant predictor. Among 71 infants never breast-fed, frequent consumption ofpeanut during pregnancy was strongly associated with peanut IgE ≥5 kU(A)/L (odds ratio, 4.99, 95% CI, 1.69-14.74; P< .004). In this cohort of infants with likely milk or egg allergy, maternal ingestion of peanut during pregnancy was strongly associated with a high level of peanut sensitization.

Trends in Milk, Egg, and Peanut IgE Levels Over Time in an Observational Study of Infants with Food Allergy (COFAR2): One Year Follow Up

RATIONALE: We enrolled 3-15 month olds (n = 512) with likely egg/milk allergy without known current peanut allergy for an observational study of food allergy. Here we report the natural course of milk, egg, and peanut specific IgE levels over the first year of observation.

Mean Wheal Size from Peanut Prick Skin Test and IgE Levels in Peanut Allergic Patients Receiving Oral Peanut Immunotherapy

Oral immunotherapy (OIT) for peanut allergy is in clinical pilot studies. The relationship between prick skin test results and serum specific peanut IgE levels could be important clinical markers for tolerance.

The CD28/CTLA-4-B7 Signaling Pathway Is Involved in Both Allergic Sensitization and Tolerance Induction to Orally Administered Peanut Proteins

Dendritic cells are believed to play an essential role in regulating the balance between immunogenic and tolerogenic responses to mucosal Ags by controlling T cell differentiation and activation via costimulatory and coinhibitory signals. The CD28/CTLA-4-CD80/CD86 signaling pathway appears to be one of the most important regulators of T cell responses but its exact role in responses to orally administered proteins remains to be elucidated. In the present study, the involvement of the CD28/CTLA-4-CD80/CD86 costimulatory pathway in the induction of allergic sensitization and oral tolerance to peanut proteins was investigated. In both an established C3H/HeOuJ mouse model of peanut hypersensitivity and an oral tolerance model to peanut, CD28/CTLA-4-CD80/CD86 interactions were blocked using the fusion protein CTLA-4Ig. To examine the relative contribution of CD80- and CD86-mediated costimulation in these models, anti-CD80 and anti-CD86 blocking Abs were used. In the hypersensitivity model, CTLA-4Ig treatment prevented the development of peanut extract-induced cytokine responses, peanut extract-specific IgG1, IgG2a, and IgE production and peanut extract-induced challenge responses. Blocking of CD80 reduced, whereas anti-CD86 treatment completely inhibited, the induction of peanut extract-specific IgE. Normal tolerance induction to peanut extract was found following CTLA-4Ig, anti-CD86, or anti-CD80 plus anti-CD86 treatment, whereas blockade of CD80 impaired the induction of oral tolerance. We show that CD28/CTLA-4-CD80/CD86 signaling is essential for the development of allergic responses to peanut and that CD86 interaction is most important in inducing peanut extract-specific IgE responses. Additionally, our data suggest that CD80 but not CD86 interaction with CTLA-4 is crucial for the induction of low dose tolerance to peanut.

Prévalence des IgE anti-CCD chez des patients sensibilisés à l'arachide

The aim of this study was to point out the existence of anti CCD specific IgE (by measurement of bromelain specific IgE) in a population of patients with both pollinosis and numerous sensitizations to food allergens. All these patients were sensitized to peanut. Three different tests were performed: measurement of specific IgE directed against bromelain, comparison of specific IgE directed against peanut before and after inhibition of the sera with bromelain, comparison of peanut blots before and after inhibition by bromelain. We showed in this study a high frequency of IgE directed against CCD in sixteen pollinics patients, polysensitized to food allergens and all considered as allergic to peanut. We studied the interference of IgE directed against CCD in the levels of specific peanut IgE response too.

Cross-reactive Carbohydrate Determinant Contributes to the False Positive IgE Antibody to Peanut

ABSTRACT Background The importance of peanut allergy has not been well recognized in Japanese society. IgE antibody to peanut can be, however, detected in patients without clinical peanut allergy. Methods Clinical characteristics of 14 patients (aged 1–8 years) with peanut allergy were evaluated. IgE antibodies to peanut from patients with and without clinical peanut allergy were compared with those to soybean and other nuts. To examine the role of cross-reactive carbohydrate determinant (CCD) on the clinically false positive detection of peanut IgE, horseradish peroxidase (HRP) and bromelain specific IgE were measured by Uni CAP IgE kit. Inhibition of peanut IgE by HRP was also examined. Results The patients repeatedly experienced potentially life-threatening symptoms, including anaphylaxis. Sera from patients with peanut allergy had negative or relatively low IgE antibodies to other nuts. However, clinically false positive peanut IgE showed significant correlation-coefficients with soybean, almond, chestnut, pistachio, macadamia and cashew ( r = 0.61–1.00). Anti-HRP and anti-bromelain IgE antibodies were detected in the clinically false positive sera, but not in the sera from patients with peanut allergy. Two out of four clinically false positive peanut IgE antibodies were significantly inhibited by HRP. Conclusions Social education about the features of peanut allergy is needed in Japan. Anti-CCD IgE antibody was suggested to be one of the mechanisms contributing to the false positive detection of peanut IgE. Detection of anti-HRP or anti-bromelain IgE can be a useful tool to recognize the presence of anti-CCD antibodies.

Relevance of casual contact with peanut butter in children with peanut allergy

Background: Casual skin contact or inhalation of peanut butter fumes is reported and feared to cause allergic reactions in highly sensitive children with peanut allergy but has not been systematically studied. Objective: We sought to determine the clinical relevance of exposure to peanut butter by means of inhalation and skin contact in children with peanut allergy. Methods: Children with significant peanut allergy (recent peanut-specific IgE antibody concentration >50 kIU/L or evidence of peanut-specific IgE antibody and one of the following: clinical anaphylaxis, a reported inhalation-contact reaction, or positive double-blind, placebo-controlled oral challenge result to peanut) underwent double-blind, placebo-controlled, randomized exposures to peanut butter by means of contact with intact skin (0.2 mL pressed flat for 1 minute) and inhalation (surface area of 6.3 square inches 12 inches from the face for 10 minutes). Placebo challenges were performed by using soy butter mixed with histamine (contact), and scent was masked with soy butter, tuna, and mint (inhalation). Results: Thirty children underwent the challenges (median age, 7.7 years; median peanut IgE level, >100 kIU/L; 13 with prior history of contact and 11 with inhalation reactions). None experienced a systemic or respiratory reaction. Erythema (3 subjects), pruritus without erythema (5 subjects), and wheal-and-flare reactions (2 subjects) developed only at the site of skin contact with peanut butter. From this number of participants, it can be stated with 96% confidence that at least 90% of highly sensitive children with peanut allergy would not experience a systemic-respiratory reaction from casual exposure to peanut butter. Conclusions: Casual exposure to peanut butter is unlikely to elicit significant allergic reactions. The results cannot be generalized to larger exposures or to contact with peanut in other forms (flour and roasted peanuts). (J Allergy Clin Immunol 2003;112:180-2.)

The natural history of peanut allergy

Background: It has traditionally been assumed that peanut allergy is rarely outgrown. Objective: The goal of this study was to determine the number of children with peanut allergy who become tolerant of peanut. Methods: Patients aged 4 to 20 years with a diagnosis of peanut allergy were evaluated by questionnaire, skin testing, and a quantitative antibody fluorescent-enzyme immunoassay. Patients who had been reaction free in the past year and had a peanut IgE (PN-IgE) level less than 20 kilounits of antibody per liter (kUA/L) were offered an open or double-blind, placebo-controlled peanut challenge. Results: A total of 223 patients were evaluated, and of those, 85 (PN-IgE < 0.35-20.4 kUA/L [median 1.42 kUA/L]) participated in an oral peanut challenge. Forty-eight (21.5%) patients had negative challenge results and were believed to have outgrown their peanut allergy (aged 4-17.5 years [median 6 years]; PN-IgE < 0.35-20.4 kUA/L [median 0.69 kUA/L]). Thirty-seven failed the challenge (aged 4-13 years [median 6.5 years]; RAST < 0.35-18.2 kUA/L [median 2.06 kUA/L]). Forty-one patients with PN-IgE levels less than 20 kUA/L declined to undergo challenge, and 97 were not eligible for challenge because their PN-IgE levels were greater than 20 kUA/L or they had had a recent reaction. Sixty-seven percent of patients with PN-IgE levels less than 2 kUA/L and 61% with levels less than 5 kUA/L had negative challenge results. Of those who underwent challenge, PN-IgE levels for those who passed versus those who failed were different at the time of challenge (P = .009), but not at the time of diagnosis (P = .25). Conclusion: This study demonstrates that peanut allergy is outgrown in about 21.5% of patients. Patients with low PN-IgE levels should be offered a peanut challenge in a medical setting to demonstrate whether they can now tolerate peanuts. (J Allergy Clin Immunol 2001;107:367-74.)