Medline ® Abstracts for References 11-14

of 'Oral food challenges for diagnosis and management of food allergies'

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Prediction of anaphylaxis during peanut food challenge: usefulness of the peanut skin prick test (SPT) and specific IgE level.
AU
Wainstein BK, Studdert J, Ziegler M, Ziegler JB
SO
Pediatr Allergy Immunol. 2010;21(4 Pt 1):603.
 
Cutoffs (decision points) of the peanut skin prick test (SPT) and specific IgE level for predicting peanut allergy have been proposed. It is not known whether decision points indicating a significant risk of severe reactions on challenge differ from those indicating probable allergy. We aimed at determining the usefulness of allergy tests for predicting the risk of anaphylaxis on challenge following the ingestion of up to 12 g of peanut in peanut-sensitized children. Children attending the Allergy Clinic who had a positive peanut SPT and completed open-label in-hospital peanut challenges were included. The challenge protocol provided for challenges to be continued beyond initial mild reactions. Eighty-nine in-hospital peanut challenges were performed. Thirty-four were excluded as the challenge was not completed, leaving 55 for analysis. Children who completed the challenge and did not react (n = 28) or reacted without anaphylaxis (n = 6) represented the comparison group (n = 34). The study group comprised 21 children whose challenge resulted in anaphylaxis. The mean peanut SPT wheal size and specific IgE level were associated with the severity of reactions on challenge. Among the 21 children, who developed anaphylaxis, in only 3 cases was anaphylaxis the initial reaction.Unexpectedly, a history of anaphylaxis was not predictive of anaphylaxis on challenge. Anaphylaxis developed at cumulative doses of peanut ranging from 0.02 to 11.7 g. Provided that a fixed amount of peanut is ingested, available tests for peanut allergy may assist in predicting the risk of anaphylaxis during challenge in peanut-sensitized children.
AD
Department of Immunology and Infectious Diseases, Sydney Children's Hospital, High Street, Randwick, Sydney, New South Wales, Australia. brynn.wainstein@sesiahs.health.nsw.gov.au
PMID
12
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The relationship of allergen-specific IgE levels and oral food challenge outcome.
AU
Perry TT, Matsui EC, Kay Conover-Walker M, Wood RA
SO
J Allergy Clin Immunol. 2004;114(1):144.
 
BACKGROUND: Oral food challenges remain the gold standard for the diagnosis of food allergy. However, clear clinical and laboratory guidelines have not been firmly established to determine when oral challenges should be performed.
OBJECTIVE: We sought to determine the value of food-specific IgE levels in predicting challenge outcome.
METHODS: A retrospective chart review of 604 food challenges in 391 children was performed. All children had food-specific IgE levels measured by means of CAP-RAST before challenge. Data were analyzed to determine the relationship between food-specific IgE levels and challenge outcome, as well as the relationship between other clinical parameters and challenge outcome.
RESULTS: Forty-five percent of milk challenges were passed compared with 57% for egg, 59% for peanut, 67% for wheat, and 72% for soy. Specific IgE levels were higher among patients who failed challenges than among those who passed (P</=.03 for each food). When seeking a specific IgE level at which a 50% pass rate could be expected, a cutoff level of 2 kUA/L was determined for milk, egg, and peanut. Data were less clear for wheat and soy. Coexistent eczema or asthma was associated with failed egg challenges, but other atopic disease was otherwise not associated with challenge outcome.
CONCLUSIONS: Allergen-specific IgE concentrations to milk, egg, and peanut and, to a lesser extent, wheat and soy serve as useful predictors of challenge outcome and should be considered when selecting patients for oral challenge to these foods.
AD
Division of Allergy and Immunology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
PMID
13
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Dose-response in double-blind, placebo-controlled oral food challenges in children with atopic dermatitis.
AU
Sicherer SH, Morrow EH, Sampson HA
SO
J Allergy Clin Immunol. 2000;105(3):582.
 
BACKGROUND: Double-blind, placebo-controlled oral food challenges (DBPCFCs) are considered the "gold standard" for diagnosing food hypersensitivity, but the dose that elicits positive challenges, or determinants that may predict dose-response relationships, have not been reported.
OBJECTIVE: Our purpose was to determine the quantity of food that elicits reactions during DBPCFCs and to evaluate parameters that may predict the provocative dose and severity of reaction.
METHODS: We reviewed challenge data for all positive challenges to 6 common allergenic foods in children with atopic dermatitis evaluated for food allergy over a 13-year period. Challenge food was generally administered in 6 doses at 10- to 15-minute intervals beginning with 400 to 500 mg and completing with a total of 8 to 10 g of food. An open feeding of a larger portion followed negative challenges. At the physician's discretion, a lower starting dose was occasionally used (100 mg, 250 mg). Food-specific IgE antibody concentrations (radioallergosorbent test [RAST]) were determined on stored sera of 20% of the challenges selected randomly and 99.6% had prick skin tests (PSTs) performed to the challenged food.
RESULTS: A total of 196 children (45% male; median age 5 y 9 mo; atopic dermatitis 98%, asthma 62%) had 513 positive challenges distributed as follows: egg 267, milk 117, soy 53, wheat 40, peanut 24, fish 12. The percentage of children reacting at the first dose (500 mg or less) was as follows: egg 49%, milk 55%, soy 28%, wheat 25%, peanut 26%, and fish 17%. Twenty-six milk challenges and 22 egg challenges were positive at a first dose of 250 mg; 3 milk challenges and 7 egg challenges were positive at a first dose of 100 mg. Eleven percent of the reactions that occurred on the first dose were severe. The percentage reacting after the final dose of the DBPCFC (or during open challenge) were egg 11%, milk 12%, soy 19%, wheat 12.5%, peanut 8.7%, and fish 25%. There was not a strong correlation between PST absolute wheal size or score (adjusted for histamine controls) and dose at reaction or severity of reaction (R(s) range -0.22 to 0.39 for particular foods). Serum concentration of food-specific IgE did not correlate well with the dose causing a reaction or with severity (R(s) range -0.40 to 0.55 for particular foods).
CONCLUSIONS: This food-allergic population may react to as little as 100 mg of food, possibly less, and the dose causing a reaction and the severity of reaction is not predicted by PST or RAST. Lower doses (100 mg or less) should be investigated for their appropriateness in initiating DBPCFCs.
AD
Elliot and Roslyn Jaffe Food Allergy Institute, Division of Allergy and Immunology, Department of Pediatrics, Mt Sinai School of Medicine, New York, NY, USA.
PMID
14
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Microarray immunoassay: association of clinical history, in vitro IgE function, and heterogeneity of allergenic peanut epitopes.
AU
Shreffler WG, Beyer K, Chu TH, Burks AW, Sampson HA
SO
J Allergy Clin Immunol. 2004;113(4):776.
 
BACKGROUND: IgE epitope mapping of food allergens is a prerequisite for engineering hypoallergenic immunotherapeutic agents and might reveal basic information regarding a patient's immune response. Mapping of large numbers of epitopes by using individual patient sera has been impractical with current techniques.
OBJECTIVE: We sought to develop a peptide microarray-based immunoassay to map peanut epitopes by using microliter quantities of serum.
METHODS: A set of 213 overlapping 20-residue peptides was synthesized corresponding to the primary sequences of Ara h 1, Ara h 2, and Ara h 3. These were arrayed in triplicate along with the corresponding recombinant proteins onto glass slides and used for immunolabeling.
RESULTS: Seventy-seven patient and 15 control sera were analyzed. The majority of patients (97%) had specific IgE to at least one of the recombinant allergens, and 87% had detectable IgE to sequential epitopes. Microarray mapping correlated well with previous studies. However, the analysis of individual patients revealed remarkable heterogeneity in the number and patterns of epitope recognition. High epitope diversity was found in patients with a history of more severe allergic reactions. Also, sensitization of effector cells with more diverse IgE antibodies conferred greater reactivity to specific allergen.
CONCLUSIONS: The protein microarray immunoassay confirmed that Ara h 1, Ara h 2, and Ara h 3 are major peanut allergens and allows for parallel epitope analysis. This has led to the discovery of an additional important epitope of Ara h 1 and the recognition of a high degree of patient heterogeneity. This qualitative difference in epitope diversity might provide prognostic information about the patient.
AD
Jaffe Food Allergy Institute, Division of Allergy and Immunology, Department of Pediatrics, Mount Sinai Medical Center, Box 1198, One Gustave L. Levy Place, New York, NY 10029, USA.
PMID