Tree Nut Cross-Reactivity Based on Clinical Allergy Testing
Monday, March 5, 2018
South Hall A2 (Convention Center)
Melissa L Robinson, DO, Neema Izadi, MD MS, Bruce J. Lanser, MD
RATIONALE: Tree nuts(TNs) are common food allergens in children and adults. Sensitization to more than one TN is often observed. Cross-reactivity between cashew/pistachio and walnut/pecan has been reported based on similar epitopes and phylogenetic homology. However, clinical cross-reactivity data is lacking. We hypothesize that clinical testing will correlate with molecular data.

METHODS: We performed a retrospective chart review from 2008 to 2017, including all patients seen at National Jewish Health with skin prick test(SPT) or serum IgE(sIgE) data for walnut/pecan or cashew/pistachio. Spearman rank correlation coefficients for sIgE and SPT were evaluated between the TN pairs. Pairings with double negative testing were excluded. OFC data for the pairs was characterized as pass or fail, with exclusion of incomplete OFCs.

RESULTS: SPTs(n=2421) for cashew/pistachio have strong correlation(rho=0.75,p<0.0001) with sIgE being even stronger(n=1754;rho=0.95,p<0.0001). Walnut/pecan SPTs(n=2051) have modest correlation(rho= 0.65,p<0.0001), while their sIgE(n=1595) have strong correlation(rho= 0.89,p<0.0001). Demographic data did not vary among groups, with a median age of 7.72 years(range 0.44-78.8 years). OFCs were performed and passed in 3 patients to both cashew and pistachio. OFCs were performed on 9 patients to walnut/pecan, with 7/9 passing both TNs, 1 failing both, and 1 passing pecan while failing walnut.

CONCLUSIONS: Based on analysis of clinical data, there is correlation between cashew/pistachio and walnut/pecan in TN-allergic patients based on SPT and sIgE, as suggested by phylogentic homology. This adds support to the common clinical practice of allowing patients who pass one TN OFC to introduce the other related TN at home, if SPT and sIgE are well-correlated.