- Letter to the Editor
- Open Access
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| Western blot analysis of native sesame OAPs fraction to confirm the absence of seed storage protein traces (a) and the specific IgE (b) and IgG sensitisation pattern (c) of all included patients. a Western-Blot analysis of an intermediate purification step (before HIC) and of the final OAPs fraction (after HIC) with sera containing sIgE to sesame seed storage proteins and oleosins. Samples were separated by SDS-PAGE using a 4–12% Bis–Tris gel and blotted onto a nitrocellulose membrane. Bound IgE were detected by anti-human IgE antibodies conjugate labelled with alkaline phosphatase; PC is a oleosin-positive serum, SP is a sesame seed storage positive serum not used in this study, sera G1b_1, 4, 14, 11, 15–18, G2_12 and 10 are sera with specific IgE to sesame seed storage proteins and partly with slightly elevated sIgE levels to sesame oleosins. b IgE sensitisation pattern to sesame extract from ImmunoCAP and EUROLINE, sesame components and oleosins from sesame, walnut, soy, hazelnut and peanut expressed as EAST (Enzyme-Allergo-Sorbent Test classification)-classes and sorted by severity of symptoms to sesame, light grey: not determined. c IgG-sensitisation pattern to sesame components and oleosins from sesame, walnut, pecan and soy expressed as EUROLINE (EL)-intensities and sorted by severity of symptoms to sesame. G1a sesame allergic patients without detectable sIgE sensitisation, G1b sesame allergic patients with sIgE sensitisation, G2 sesame tolerant patients with sIgE sensitisation, PC positive control selected by sIgE to sesame oleosins, C1-3 positive controls selected by sIgE to peanut oleosins |
Abstract
Background
In daily practice, one-third of sesame allergic patients, confirmed by clinical history or food challenge, do not show any detectable specific IgE using current diagnostics. Currently used sesame extracts are water-based and therefore lacking hydrophobic proteins like oleosins.
Oleosins, the stabilizer of lipid droplets in plants, are described as allergens in sesame, peanut and hazelnut. In this study, we examine the role of oleosins in sesame allergy and their potential cross-reactivity between sesame and (pea)nuts.
Methods
Specific IgE and IgG sensitisation to native and heterologously expressed sesame components and oleosins from other nuts, free of seed storage proteins, was assessed by line blot and sera from 17 sesame allergic patients without detectable specific IgE sensitisation to sesame, and compared to 18 sesame allergic and 13 tolerant patients with specific IgE sensitisation to sesame.
Results
Sesame allergic patients without sensitisation showed no specific IgE to the tested sesame oleosins or components. Low levels of specific IgE to sesame oleosins were detected in 17% of sesame allergic and 15% of tolerant patients with sIgE sensitisation. Oleosins were recognised by serum IgG from multiple patients confirming immune reactivity and excluding technical issues leading to lack of specific IgE-binding to oleosins.
Conclusion
Sesame oleosins are minor allergens and appear to have no additonal value in diagnosing sesame allergy in adults based on sIgE and sIgG detection. There is a high need for additional diagnostic tools in those patients to minimize the number of required food challenges.
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