Researchers refine testing method for cashew allergy

23 December 2021

2 minutes to read


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According to a study published in Annals of Allergy, Asthma and Immunology.

Petteri Röntynen, MD, from the University of Helsinki and the University Hospital of Helsinki, and colleagues evaluated the usefulness of various tests in the assessment of pediatric cashew allergy, including specific IgE (sIgE) at Ana o 3, cashew sIgEs, skin tests, basophil activation tests and serum tryptase measurement, as well as combinations thereof.

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The study involved 106 children (median age, 5.04 years; age range, 1.41 to 6.66 years; 21.7% under 3 years old; 48% boys) suspected of allergy with cashew nuts.

The researchers took a blood sample from each participant before undergoing an oral food challenge. In addition, the researchers assessed baseline tryptase and complete blood count before each challenge and 60, 120, and 240 minutes after the onset of significant allergic symptoms.

The researchers also performed a SPT on each child’s forearm for cashew and nine other nuts as well as for birch before each OFC. BAT was also carried out for cashews before each OFC.

During OFC, each patient received 50 mg, 100 mg and 500 mg of raw cashew protein at 30 minute intervals, with a cumulative dose of 680 mg of cashew protein, or 3.5 nuts. of cashew. CFOs were stopped when significant objective or subjective symptoms appeared. The median cumulative reactive dose was 80 mg of protein.

After OFC, 72 children (68%) developed symptoms related to cashew protein, of which 14 (19%) were classified as mild, 26 (36%) as moderate, and 32 (44%) as moderate. serious. Additionally, 34 children (47%) presented positive challenge reactions defined as anaphylactic, while 19 (29%) presented negative challenges despite a reliable history of a previous reaction.

Researchers found a moderate negative correlation between cumulative reactive dose and Ana o 3-IgE (Spearman’s rho, -0.583) and SPT cashew (Spearman’s rho, -0.545).

However, researchers observed a weak negative correlation between cumulative reactive dose and cashew IgE (Spearman’s rho, -0.493) and the percentage of CD63 + basophils (BAT%; Spearman’s rho, -0.469).

In addition, the severity score was correlated with cashew SPT (Spearman’s rho, 0.412), BAT% (Spearman’s rho, 0.448), Ana o 3-IgE (Spearman’s rho, 0.338) and walnut IgE. cashew (Spearman’s rho, 0.379).

An MTD of 22.8% or greater best predicted reaction severity with specificity of 91.7% and sensitivity of 60.7% but, the researchers noted, cutoffs were age specific. The utility of BAT, they added, has been best demonstrated in children aged 5 years and older, which could help providers decide the optimal time for the cashew challenge to avoid reactions. severe allergic.

The researchers also noted that PTS was well associated with severity, especially in older children, and was associated with lower costs and greater availability than MTD.

But overall, the researchers wrote, Ana o 3-IgE appeared to be the best single test to diagnose cashew allergy, with a cutoff of 0.97 kU / L showing specificity of 94.1. % and a sensitivity of 61.1%. Various combinations of tests did not improve diagnostic values.


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