The following is a summary of “Ara h 2 Peptide Mix Improves the Diagnosis of Peanut Allergy and Is Relevant for Ara h 2–Induced Mast Cell Activation,” published in the November 2023  issue of Allergy and Clinical Immunology by Kwok, et al.

It was very important to get a correct evaluation of peanut allergy.  Researchers found 4 Ara h 2 peptides, making Ara h 2-specific IgE (sIgE) diagnostics more accurate. For a study, they sought to see how well sIgE can be used to diagnose this mix of peptides and what role they play in mast cell reaction to peanut allergens. ImmunoCAP was used to find the sIgE to the peptide mix. It was tested to see how well it could diagnose with Ara h 2-sIgE and sIgE to the different peptides. To see if the peptides were useful, they were put through a mast cell activation test using a laboratory of allergic diseases 2 cell line and flow cytometry. 

A total of 92 were studied: 52 were peanut-allergic (PA), 36 were peanut-sensitized but tolerant, and 9 were not sensitive to peanuts and were not allergic. The diagnostic accuracy of Ara h 2-sIgE was better with peptide mix-sIgE than with Ara h 2-sIgE alone (area under the receiver operating characteristic curve =.92 vs..89; P =.056). For Ara h 2-sIgE mixed with the peptide mix, the sensitivity was 85%, and the specificity was 96%. The specificity of sIgE to single peptides was best (91%–96%), but the sensitivity was lowest (10%–52%). This was compared to Ara h 2-sIgE (69% specificity and 87% sensitivity) and peptide mix-sIgE (82% specificity and 63% sensitivity).  

Peptide 3 directly activated mast cells, and the peptide mix stopped Ara h 2 from activating mast cells stimulated with plasma from PA patients who were positive for Ara h 2. It was the same for sIgE to individual peptides and sIgE to the mix of peptides, improving the diagnostic performance of Ara h 2-sIgE.  The peptides stopped Ara h 2 from activating mast cells, which proved that it is important in peanut allergies.

Source: sciencedirect.com/science/article/pii/S2213219823007961