Utility of specific IgE to Ara h 6 in peanut allergy diagnosis.

BACKGROUND: Specific IgE to Ara h 2 has been shown to be useful in the diagnosis of peanut allergy, whereas the peanut lipid transfer protein, Ara h 9, has been suggested to be responsible for peanut allergy in the Mediterranean population. OBJECTIVE: To better characterize peanut allergy in children from a Mediterranean area and determine the value of specific IgE to Ara h 6 (conglutinin, 2S albumin) for the diagnosis of peanut allergy. METHODS: Ninety-one children with suspected allergy to edible vegetables were included in the study. They were classified as allergic or tolerant to peanut. Specific IgE to peanut allergens was measured by a commercially available microarray (ImmunoCAP ISAC 112, ThermoFisher, Uppsala, Sweden). RESULTS: Patients allergic to peanut showed positive specific IgE changes to peanut seed storage proteins (Ara h 1, Ara h 2, Ara h 3, and Ara h 6) more frequently than tolerant subjects. Ara h 9 showed a similar frequency of reactivity in the 2 groups. Ara h 6 was the allergen most frequently recognized by patients with allergy. Four patients with allergy were found to be mono-sensitized to Ara h 6. Ara h 2 and Ara h 6 showed similar diagnostic accuracy (areas under the curve 0.792 and 0.852). A combined cutoff point for Ara h 2 (≥0.1 ISU) and Ara h 6 (≥2 ISU) yielded the best diagnostic performance (sensitivity 0.77, specificity 0.97, positive predictive value 0.89, negative predictive value 0.93). CONCLUSION: Peanut allergy cannot be ruled out without obtaining a negative determination of Ara h 6.

Shellfish Allergy: a Comprehensive Review.

Shellfish allergy is of increasing concern, as its prevalence has risen in recent years. Many advances have been made in allergen characterization. B cell epitopes in the major allergen tropomyosin have been characterized. In addition to tropomyosin, arginine kinase, sarcoplasmic calcium-binding protein, and myosin light chain have recently been reported in shellfish. All are proteins that play a role in muscular contraction. Additional allergens such as hemocyanin have also been described. The effect of processing methods on these allergens has been studied, revealing thermal stability and resistance to peptic digestion in some cases. Modifications after Maillard reactions have also been addressed, although in some cases with conflicting results. In recent years, new hypoallergenic molecules have been developed, which constitute a new therapeutic approach to allergic disorders. A recombinant hypoallergenic tropomyosin has been developed, which opens a new avenue in the treatment of shellfish allergy. Cross-reactivity with species that are not closely related is common in shellfish-allergic patients, as many of shellfish allergens are widely distributed panallergens in invertebrates. Cross-reactivity with house dust mites is well known, but other species can also be involved in this phenomenon.

Peach allergy in Spanish children: tolerance to the pulp and molecular sensitization profile.

BACKGROUND: Peach allergy is the main cause of vegetable food allergy in the Mediterranean area. Pru p 3 is the major allergen, and it is mainly found in the peel. OBJECTIVE: We sought to calculate the frequency of tolerance to peach pulp in Spanish children suffering from allergic reactions after eating or having contact with peach and to analyze the sensitization pattern to peach allergens. METHODS: Fifty-seven children (32 boys; median age, 7.4 yr) were included in the study. A systematized questionnaire on allergic reactions to peach was administered. Prick tests with peach peel and pulp, peach lipid transfer protein (LTP), and profilin were performed. Serum-specific IgE to peach, rPru p 1, rPru p 3, and rPru p 4 was determined by ImmunoCAP. Oral food challenges (OFCs) with peach pulp were performed on all but one child. RESULTS: Eighty-eight percent of the children had positive prick tests with peach peel, 35% with peach pulp, 88% with peach LTP, and 9% with profilin. Serum-specific IgE to peach was demonstrated in 100% of the patients; rPru p 3-specific IgE in 96%; rPru p 1-specific IgE in 11%; and rPru p 4-specific IgE in 10%. Oral food challenge was negative in 52 (93%) children. CONCLUSIONS: More than 90% of the study population tolerated peeled peach. Pru p 3 was the major allergen. Pru p 1 and 4 showed low prevalence.

Efficacy and safety of oral desensitization in children with cow's milk allergy according to their serum specific IgE level.

BACKGROUND: Oral desensitization in children allergic to cow's milk proteins is not risk free. The analysis of factors that may influence the outcome is of utmost importance. OBJECTIVE: To analyze the efficacy and safety of the oral desensitization according to specific IgE (sIgE) level and adverse events during the maintenance phase. METHODS: Thirty-six patients allergic to cow's milk (mean age, 7 years) were included in an oral desensitization protocol. Patients were grouped according to sIgE levels (ImmunoCAP) into groups 1 (sIgE <3.5 kU/L), 2 (3.5-17 kU/L), and 3 (>17-50 kU/L). Nineteen children were included as a control group. Serum sIgE levels to cow's milk and its proteins were determined at inclusion and 6 and 12 months after finishing the desensitization protocol. RESULTS: Thirty-three of 36 patients were successfully desensitized (200 mL): 100% of group 1 and 88% of groups 2 and 3. Desensitization was achieved in a median of 3 months (range, 1-12 months); 90% of the patients in group 1, 50% of the patients in group 2, and 30% of the patients in group 3 achieved tolerance in less than 3 months (P = .04). In the control group only 1 child tolerated milk in oral food challenge after 1 year. During the induction phase, there were 53 adverse events in 27 patients (75%). Patients of groups 2 and 3 had more severe adverse events compared with group 1. During the maintenance phase, 20 of 33 patients (60%) had an adverse event. CONCLUSION: Oral desensitization is efficacious. Tolerance is achieved earlier when sIgE is lower. Severe adverse events are frequent, especially in patients with higher sIgE levels.

Accidental allergic reactions in children allergic to cow's milk proteins.

BACKGROUND: Cow's milk is the main cause of food allergy in children. Patients allergic to food frequently experience accidental exposure. There are few studies analyzing this problem, most of them concerning peanut allergy. OBJECTIVE: We sought to calculate the frequency of accidental exposure reactions in children allergic to cow's milk during a 12-month period, to analyze the clinical characteristics and circumstances surrounding the reactions, and to identify risk factors for severe reactions. METHODS: Eighty-eight children allergic to cow's milk (44 boys; median age, 32.5 months) were included in the study. A systematized questionnaire about accidental exposure was used. Reactions were classified as mild, moderate, and severe. Cow's milk- and casein-specific IgE antibody titers were determined. RESULTS: Thirty-five (40%) children had 53 reactions in the previous year (53% mild, 32% moderate, and 15% severe). Most reactions took place at home (47%) under daily life circumstances (85%). Specific IgE levels to cow's milk were higher in children with severe reactions than in those with moderate (median, 37.70 vs 7.71 KUA/L; P = .04) or mild (3.37 KUA/L; P = .04) reactions. The frequency of severe reactions was 10-fold higher in asthmatic children (odds ratio, 10.2; 95% CI, 1.13-91.54). CONCLUSIONS: Reactions to accidental exposure are frequent in children with cow's milk allergy. The proportion of severe reactions was 15%. The risk factors for such reactions included very high levels of specific IgE to cow's milk and casein and asthma.

Prediction of tolerance on the basis of quantification of egg white-specific IgE antibodies in children with egg allergy.

BACKGROUND: It is thought that the natural evolution of food allergy has a good tolerance prognosis. However, there are few follow-up studies that determine the exact probability of tolerance to a given food or that analyze prognostic factors that can help us to understand the evolution of a child who begins life with a food allergy. OBJECTIVE: We sought to determine the likelihood that children younger than 2 years of age with allergy to egg would eventually have tolerance to it and to analyze several prognostic predictors using egg white-specific IgE level as the main variable. METHODS: We performed a prospective study of 58 children younger than 2 years of age with egg allergy, who were studied periodically until tolerance developed or until the end of the study. During the follow-up period, open challenge tests were carried out according to previously established criteria to verify tolerance to egg. Factors such as egg white-specific IgE level, serum total IgE level, symptoms after egg ingestion, size of skin prick test reactions to egg white, atopic dermatitis, and sex were analyzed as prognostic markers. Kaplan-Meier survival curves were used to calculate cumulative tolerance probability. Predictor influence and relative prognostic importance were estimated with the Cox proportional regression model. RESULTS: The median time from the appearance of the first symptoms to tolerance was 35 months. Cumulative tolerance probability was 16% at 12 months of follow-up, 28% at 24 months, 52% at 36 months, 57% at 48 months, and 66% at 60 months. The relative weight of prognostic factors, expressed as the hazard ratio, was 50.95 for symptoms and 3.74 for the size of skin prick test reactions, with both being independent effects. The hazard ratio was 1.173 for every 0.1-unit decrease in the concentration log (decimal logarithm) of specific IgE level, with this effect being associated with tolerance only in children with cutaneous symptoms. CONCLUSIONS: Half of the children younger than 2 years of age with egg allergy will tolerate the food at 35 months of follow-up, and the proportion could be 66% after 5 years. At that age, the main predictors were the symptoms experienced after egg ingestion, followed by the size of skin prick test reactions. In addition, the specific IgE antibody level is an important prognostic marker in children who only had cutaneous symptoms.