D1.12 - Cross-Reactivity Between Peach Juice and Cupressaceae Pollen

Peach allergy is most commonly mediated by lipid-transfer protein (Pru p 3), profilin or gibberellin-regulatedproteins (Pru p 7). However, some patients present systemic reactions despite negative molecular IgE testing. We present a teenager who developed urticaria, angioedema, and dyspnoea after peach juice ingestion, with allergenic characterization pointing to unexpected cross-reactivity with Cupressaceae pollen.

A 16-year-old girl experienced two systemic allergic reactions after drinking commercial peachjuice, with a previous reaction after nectarine ingestion. Skin prick-prick tests were negative for all Rosaceae fruits tested except for peach pulp. Specific IgE to Pru p 3, Pru p 4, and Pru p 7 was negative. IgE–Western blot was performed to identify IgE-binding components. In addition, an inhibition Western blot was conducted using Cupressaceae pollen extracts.

Western blot analysis under non-reducing conditions revealed a ~12 kDa band in peach juice compatible with Pru p 7 (GRP), despite negative sIgE to Pru p 7 (Figure 1). This discrepancy may be explained by the lower sensitivity of single-component IgE testing in patients with low levels or co-sensitized patients. Multiple high-molecular-weight bands (>37 kDa) were also detected in all extracts, with greater intensity in the sediment under reducing conditions. The ~40 kDa band is consistent with ENEA, a recently described peach/apricot allergen (SDS-PAGE migration ~41 kDa; true mass ~18.3 kDa). The ~45 kDa band aligns with published evidence of a peach–cypress cross-reactive allergen independent of GRP. The ~65 kDa band matches recent literature describing an (R)-mandelonitrile lyase as a candidate peach allergen. Inhibition Western blot showed that all Cupressaceae pollens inhibited IgE binding not only to Prup 7 but also to the higher molecular weight proteins, confirming broad cross-reactivity between peach juice allergens and Cupressaceae pollen.

This case demonstrates that systemic reactions to peach juice in this patient were likely driven by asynergistic sensitization to multiple peach allergens, including Pru p 7, ENEA, and other proteins exhibiting functional cross-reactivity to Cupressaceae pollen. These findings support the presence of clinically relevant allergens shared between peach and cypress pollen, potentially enhanced by the high Cupressaceae pollen burden in the patient’s geographical area.