Tree nut component testing.
A few months ago, I asked Dr. Silver (Cleveland) about component testing for tree nuts. He referred to a brochure put out by Thermo Scientific (the makers of the ImmunoCAP and the Component Testing) for physicians.
With permission, his response:
“It lists the relevant tree nut components (cashew, walnut, hazelnut, and brazil nut) and tries to offer some kind of an interpretation for the results. It does not offer any info regarding how high a component sensitization ought to be in order to considered clinically significant.
There are only a few studies available to guide doctors with the clinically-relevant IgE “cut off” values for a given component. Unlike the new tree nut components, the peanut ARA H2 component has been more extensively studied, and the cut off antibody levels for clinical decisions are well documented.
Practically, I would check the tree nut component levels when I am not certain whether or not a patient is truly allergic to a given nut. If the component values are high (based on the latest published studies), we would avoid an oral challenge and (may) recommend enrollment in OIT. If the component sensitization levels is below the relevant threshold, then we may challenge the nut in the office and ought right remove the concern of food allergy.” Dr. Eli Silver
Example: If patients test positive to walnut, but negative to components Jug r1 and Jug r3, then they could be cross-reactive to pollen or “carbohydrate determinants.” Walnut allergies are rarely outgrown.
A few weeks later, Dr. LaRussa (Alabama), regarding to hazelnut, referred to the “puzzle of tree nut components.”
Positive test results to certain proteins of the hazelnut might indicate a birch (1) or a peach (8) cross-reaction, whereas (9) and (14) indicate a higher risk and “true” allergy.
For more information, please speak with your OIT specialist.