Making the Most of In Vitro Tests to Diagnose Food Allergy

Abstract

Various in vitro tests assess different aspects of the underlying immune mechanism of IgE-mediated food allergy. Some can be used for diagnostic purposes; specific IgE to allergen extracts is widely available; specific IgE to allergen components is used in most specialist centers, and the basophil activation test is becoming increasingly used clinically. IgE to allergen peptides, T-cell assays, allergen-specific/total IgE ratios, and allergen-specific IgG4/IgE ratios are currently reserved for research. Different factors can modulate the likelihood of IgE-mediated food allergy of a given allergy test result, namely, the patients' age, ethnicity, previous allergic reaction to the identified food, concomitant atopic conditions, and geographical location, and need to be taken into account when interpreting the allergy test results in the clinic. The importance of the specific food, the clinical resources available, and patient preferences are additional aspects that need to be considered when deciding whether an oral food challenge is required to reach an accurate diagnosis of IgE-mediated food allergy.

Keywords: Basophil activation test; Component-resolved diagnosis; Diagnosis; Food allergy; IgG4/IgE ratio; In vitro tests; Peptide microarray; Specific IgE; Specific/total IgE ratio; T-cell assay.

Figure 1

Tests used to diagnose IgE-mediated food allergy reflect different aspects of the underlying mechanism of this immune-mediated disorder: the skin prick test measures the response of skin mast cells to allergen, the basophil activation test measures the response of circulating basophils to allergen, and IgE tests measure the concentration of circulating IgE, either total IgE or sIgE to allergen extracts or to individual allergen components. Total IgE and allergen-specific IgG4 can be used to calculate ratios with allergen sIgE.