Exploring Correlations Between Cross-Reactive Tree Nuts in Multiple Food Allergic Patients

Rationale: The study’s aim is to determine whether correlations exist in the outcome of oral food challenges for cashew and pistachio as well as walnut and pecan in patients with multiple food allergies.

Methods: Suspected cashew/pistachio and/or walnut/pecan allergies were examined in 60 patients using specific IgE (n=43 and n=34) measurements, skin prick tests (n=47 and n=34), and double blind placebo controlled food challenges (n=42 and n=30), respectively.  Food flours were administered in staged, validated, blinded food challenges using the following dosage amounts: 5 mg, 20 mg, 50 mg, 100 mg, 100 mg, 100 mg, and 125 mg for a cumulative dose of 500 mg. Specific IgE, skin prick test (average wheal size in mm), and eliciting dose for walnut/pecan and cashew/pistachio was analyzed using the Pearson correlation coefficient. 

Results: Specific IgE and skin prick tests highly correlated between cashew and pistachio (r=0.93 and r=0.77, p<0.001, respectively) and between walnut and pecan (r=0.78 and r=0.64, p<0.001, respectively). All patients who underwent oral food challenge for cashew and pistachio (n=42) and for walnut and pecan (n=31) were positive for both. However, only moderate correlation was found between the eliciting dose  of the food challenge of walnut and pecan (r=0.4, p=0.02) and no correlation was found between cashew and pistachio.

Conclusions: Although high correlation was found in skin prick tests and specific IgE between cashew/ and pistachio and between walnut/ and pecan in multiple food allergic patients, the eliciting dose for one allergen was not correlated with the other.