IgE Cross-Reactivity between Humulus japonicus and Humulus lupulus

Area of Science:

• Allergen immunotherapy
• Environmental allergy
• Immunology

Background:

• Japanese hop (Humulus japonicus) is a primary cause of pollinosis in East Asia.
• Limited clinical supply of Japanese hop allergen extract necessitates exploring alternatives.
• Common hop (Humulus lupulus) pollen is a potential substitute if IgE cross-reactivity is high.

Purpose of the Study:

• To compare IgE cross-reactivity and allergenicity between Japanese hop and common hop pollen.
• To determine if common hop pollen can serve as an alternative allergen source.
• To investigate the allergenic components of both hop species.

Main Methods:

• Inhibition ELISA was used to measure IgE cross-reactivity.
• One- and two-dimensional gel electrophoresis with IgE immunoblotting were performed.
• Liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) identified IgE-reactive components.

Main Results:

• Common hop pollen demonstrated minimal inhibition (up to 16.7%) of IgE reactivity to Japanese hop.
• A key 12-kDa allergenic protein in Japanese hop pollen was not found in common hop.
• Six IgE-reactive components in Japanese hop pollen were detected but could not be definitively identified via mass spectrometry.

Conclusions:

• There is no significant IgE cross-reaction between Japanese hop and common hop pollen allergens.
• Current common hop pollen is unsuitable as an alternative for Japanese hop allergy diagnostics or immunotherapy.
• Urgent development of diagnostic and immunotherapeutic reagents specific to Japanese hop pollen is required.