sIgE Ana o 1, 2 and 3 accurately distinguish tolerant from allergic children sensitized to cashew nuts.
BACKGROUND
The double-blind, placebo-controlled food challenge test (DBPCFC) is the gold standard in cashew nut allergy. This test is costly, time consuming and not without side effects. Analysis of IgE reactivity to cashew nut components may reduce the need for food challenge tests.


METHODS
In a prospective and multicentre study, children with suspected cashew nut allergy underwent a DBPCFC with cashew nut. Specific IgE to cashew nut and to the components Ana o 1, 2 and 3 were determined. A skin prick test (SPT) with cashew nut extract was performed. The association between the outcome of the food challenge test and specific IgE to Ana o 1, 2 and 3 was assessed with logistic regression analyses, unadjusted and adjusted for other diagnostic variables. Discriminative ability was quantified with a concordance index (c).


RESULTS
A total of 173 children (103 boys, 60%) with a median age of 9 years were included. About 79% had a positive challenge test outcome. A steep rise in the risk of a positive challenge was observed for specific IgE to each individual component Ana o 1, 2 and 3 with estimated risks up to approximately 100%. Median values of Ana o 1, 2, 3 were 1.29 kU/l (range 0-100 kU/l), 4.77 kU/l (range 0-100 kU/l) and 8.33 kU/l (range 0-100 kU/l) respectively and varied significantly (p < 0.001). Specific IgE to Ana o 1, 2 and 3 was better distinguished between cashew-allergic and tolerant children (c = 0.87, 0.85 and 0.89, respectively) than specific IgE to cashew nut or SPT (c = 0.76 and 0.83, respectively).


CONCLUSION
The major cashew nut allergens Ana o 1, 2 and 3 are each individually predictive for the outcome of food challenge tests in cashew-allergic children.
['van der Valk|J P M|JP|', 'Gerth van Wijk|R|R|', 'Vergouwe|Y|Y|', 'Steyerberg|E W|EW|', 'Reitsma|M|M|', 'Wichers|H J|HJ|', 'Savelkoul|H F J|HF|', 'Vlieg-Boerstra|B|B|', 'de Groot|H|H|', 'Dubois|A E J|AE|', 'de Jong|N W|NW|']
D000485:Allergens D031021:Anacardium D052179:Antigens, Plant D015415:Biomarkers D002648:Child D002675:Child, Preschool D005260:Female D006801:Humans D007073:Immunoglobulin E D008297:Male D021184:Nut Hypersensitivity D009754:Nuts D010940:Plant Proteins D011446:Prospective Studies D012882:Skin Tests
children food challenge test cashew nut allergy components Ana o 1 Ana o 2 and Ana o 3 component-resolved diagnosis