Intracellular Expression of Fluorochrome Labelled-Diamine Oxidase in Basophils: A Novel Diagnostic Tool for Peanut Allergy
Sunday, March 6, 2016
South Exhibit Hall H (Convention Center)
Yasmin R. Mohseni, B.Sc, Paul J. Turner, FRACP PhD, Robert J. Boyle, MBChB PhD, Andrew Clark, MRCPCH MD, Abigail O Robb, B.Sc, Stephen R. Durham, MA MD FRCP, Mohamed H. Shamji, BSc MSc PhD FAAAAI

Peanut allergy is a leading cause of fatal anaphylaxis. Labelled intracellular Diamine Oxidase (DAO) has been used to measure basophil histamine release at a single cell level. We hypothesized that the intracellular DAO assay can be used a functional diagnostic tool for identifying peanut allergic patients, and monitor basophil response following an oral peanut challenge, which may improve our ability to predict those at risk of anaphylaxis. 


Basophil activation and histamine release was measured in peanut allergic patients (n=10), peanut sensitized (n=4) undergoing an oral food challenge and non-atopic controls (n=10) by expression of CD63 and intracellular DAO by flow cytometry. Additionally, basophil responses were measured before, during and after in vivo peanut challenge. 


CD63+CRTh2+ basophils were significantly increased and DAO+CD63-CRTh2+ basophils were decreased in peanut allergic compared to non-allergics (P<0.001, P<0.001). A strong correlation was observed between basophil activation and degranulation (r=-0.9140, P<0.0001). There was an increasing trend in basophil activation and degranulation during in vivo active peanut challenge. ROC analysis revealed the assay cut off for DAO assay was 93.9%, with clinical sensitivity 92.9% and specificity of 90%, with the likelihood ratio of 9.29. For CD63, this was 2.7%, with clinical sensitivity and specificity of 85.7% and 90% respectively, and likelihood ratio of 8.57.


In this pilot study, we show for the first time that the DAO assay used in conjunction with CD63 may potentially be utilised to distinguish peanut allergic from non allergic individuals.