IgE-binding to vicilin-like antimicrobial peptides is associated with systemic reactions to macadamia nut

Abstract

Background Macadamia nut can induce fatal allergic reactions and changes in dietary habits will raise their consumption in industrialised countries. Until now diagnosis of macadamia nut allergy by sIgE solely relies on the macadamia nut extract, but single components are lacking. Methods Macadamia nut proteins recognised by IgE from 2 macadamia nut extract positive sera were identified by mass spectrometry (vicilin-like antimicrobial peptides: VLAP). Sensitisation to macadamia nut extract and heterologously expressed isoform VLAP-2–3 was evaluated in 82 nut allergic (NA) and 27 tolerant (NT) patients (no tree nut allergy reported) comprehending 10 macadamia nut allergic (MA) and 18 explicitly reported macadamia nut tolerant patients (MT), using line blots. Co-sensitisation to additional VLAP isoforms and other vicilins was evaluated in 8 MA, 12 MT and 14 NA patients sensitised to VLAP-2–3. Functional properties were determined by indirect basophil activation. Results Even though proteins recognised by IgE were identified as VLAP-2–1, 2–2 and 2–3, only peptides specifically belonging to VLAP-2–3 were detected by mass spectrometry. The macadamia nut extract was recognised by 33% of NA patients (27/82) including 3 MA patients and 26% of NT patients (7/27, 3 MT). Similarly, 29% of NA (24/82) patients showed partly strong sIgE-binding to VLAP-2–3 including 3 MA patients with systemic reactions to macadamia nut. Contrary, VLAP-2–3 was recognised by only 2 NT (1 MT) patients (7%) with very low sIgE titres. Simultaneous recognition of the isoforms VLAP-2–1 and 2–2 was observed in all patients positive for VLAP-2–3 with partly reduced sIgE titres in 59% of these patients. Additionally, all three VLAP isoforms were able to repeatedly induce BAT reactivity upon sensitisation with a MA serum. Conclusion VLAP proteins are the first described macadamia nut components with serological and functional allergenic properties and they are associated with systemic reactions to macadamia nut.

Macadamia nut‐specific IgE levels for predicting anaphylaxis

“…Although Mac i 1‐sIgE reportedly has better diagnostic ability than the crude Md‐sIgE, the relationship between the results of these laboratory tests and the severity of the allergic reactions has not been assessed 28 . Ehlers et al 29 have recently reported that Mac i 1 is associated with systemic reactions to Md. As we did not measure the Mac i 1 levels, therefore, we could not analyze the components that caused anaphylaxis.…”

Unbiased Immunization Strategy Yielding Specific Nanobodies against Macadamia Allergen of Vicilin-like Protein for Immunoassay Development

“…Two bands enriched by Nb-based Co-IP were identified as MiAMP2. The vicilin protein is abundant in macadamia nuts serving as a seed storage protein, and it is often associated with allergic reactions described in the literature. , One of the Nb target proteins has been identified recently as a novel food allergen named Mac i 1. Hence, MiAMP2 has the potential to serve as a marker for macadamia nut contamination.…”

Molekulare Komponentendiagnostik in der pädiatrischen Allergologie

“…Die Speicherproteine Ber e1 (2 S-Albumin) und Ber e2 (11 S-Globulin) können die Sensitivität der Diagnostik im Vergleich zum Gesamtextrakt erhöhen. Auch Macadamiaallergien sind seltenhier scheinen vicilinähnliche antimikrobielle Peptide ursächlich zu sein [16,17].…”