sIgE Ana o 1, 2 and 3 accurately distinguish tolerant from allergic children sensitised to cashew nuts

Abstract

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

173 children (103 boys, 60%) with a median age of 9 years were included. 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 6.0 kU/l (range 0-100 kU/l), 13.6 kU/l (range 0-100 kU/l) and 22.2 kU/l (range 0-100 kU/l) respectively and varied significantly (p < 0.001). Specific IgE to Ana o 1, 2 and 3 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.

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