Quantification of specific IgE to whole peanut extract and peanut components in prediction of peanut allergy
University of Manchester, Manchester Academic Health Science Centre, NIHR Translational Research Facility in Respiratory Medicine, University Hospital of South Manchester NHS Foundation Trust, Manchester, United Kingdom. The Journal of allergy and clinical immunology
(Impact Factor: 11.48).
03/2011; 127(3):684-5. DOI: 10.1016/j.jaci.2010.12.012
Available from: samj.org.za
- "A cost-effective approach to component testing in this population would therefore be to test Ara h 2 and Ara h 9. Ninety-five percent PPVs have been developed as a surrogate to oral food challenges, and also to minimise the overdiagnosis of food allergy based on laboratory results alone. Although there is some variation of PPVs for peanut allergy in the international literature, a specific IgE level of ≥14 kU/L is commonly used,as is an SPT value of >8 mm.In a recent British study, an excellent performance of Ara h 2 Immuno- CAP was attained, with 97.5% of patients correctly classified as peanut allergic v. tolerant at a cut-off of 0.35 kU/L.However, 95% PPVs may be age and population specific. "
Available from: Ole D Wolthers
- "IgE sensibilization to Ara h2 often correlates with positive IgE against Ara h1 and Ara h3. If there are IgE antibodies in serum to Ara h2 and/or Ara h1/Ara h3, more than 95% of the patients will have symptoms when ingesting peanuts . If there is IgE only to Ara h2 and not to Ara h1, 3 or 8 87% report symptoms. "
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ABSTRACT: Component resolved diagnosis is a new concept in the investigation of pediatric allergic disease. The aim of the present paper is to review the available data on component resolved diagnosis with respect to implications for investigation of children with allergic disease. In most conditions head-to-head comparisons of component resolved diagnosis with traditional IgE testing have not been performed. Rather than alternatives the molecular methods should be seen as adjuncts to the cheaper traditional specific IgE tests. It may be appropriate to determine IgE antibodies to components as part of the diagnostic work-up in selected cases of peanut and birch pollen allergy and in hymenoptera allergy. However, cost benefit analyses of component resolved diagnosis compared with traditional work-up of allergy are needed. Prospectively planned protocols for assessment of the extent to which component resolved diagnosis may be able to improve the selection of children to immunotherapy and, thus, the efficacy of immunotherapy, are needed. Finally, studies of component resolved diagnosis with microarray technology in screening panels with hundreds of components should be undertaken before it can be determined to which extent such panel screening, if at all, may be helpful in children.
Available from: ncbi.nlm.nih.gov
- "We did not reproduce the results seen by Nicalou et al. Their study also used a specific IgE cutoff of 15 kU/L but had 96% of subjects at greater than this level being correctly classified as allergic while we only demonstrated a correct diagnosis of 48% (31 with IgE > 15 kU/L of 64 that had a reaction) (Nicalou, 2011 "
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ABSTRACT: AIMS: To determine whether specific IgE and skin prick test correlate better in predicting reaction severity during a double-blinded placebo controlled food challenge (DBPCFC) for egg, milk, and multiple tree nut allergens. STUDY DESIGN: Prospective study. PLACE AND DURATION OF STUDY: Department of Pediatrics, Stanford University School of Medicine, August 2009 and ongoing. METHODOLOGY: We examined the reaction severity of twenty-four subjects to nine possible food allergens: milk, egg, almond, cashew, hazelnut, peanut, sesame, pecan and walnut. Specific IgE and SPT were performed before each DBPCFC. DBPCFC results were classified into mild (1), moderate (2), or severe (3) reactions using a modified Bock's criteria. RESULTS: Twenty four subjects underwent a total of 80 DBPCFC. Eighty percent of all DBPCFCs resulted in a positive reaction. A majority, 71%, were classified as mild. No reactions occurred with a SPT of zero mm while three reactions occurred with a negative specific IgE. All reactions were reversible with medication. CONCLUSION: These data suggest that SPT and specific IgE levels are not associated with reaction severity (p<0.64 and 0.27, respectively). We also found that combining specific IgE and SPT improved specificity but did not help to achieve clinically useful sensitivity. For instance, an SPT > 5mm had a sensitivity of 91% and specificity of 50%. Combining SPT > 5mm and IgE > 7 resulted in a reduced sensitivity of 64%. Unexpectedly, a history of anaphylaxis 70% (n=17) was not predictive of anaphylaxis on challenge 4% (n=2).
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