IgE Cross-Reactivity between Humulus japonicus and Humulus lupulus

PURPOSE: Japanese hop (Humulus japonicus) is a major cause of weed pollinosis in East Asia. However, supplies of commercial allergen extract from this plant have not met clinical demand. The pollen of common hop (Humulus lupulus), a closely related species, may provide an alternative source if there is strong IgE cross-reactivity between these two species. We aimed to compare the IgE cross-reactivity and allergenicity of common hop and Japanese hop pollen. MATERIALS AND METHODS: Cross-reactivity was measured by inhibition ELISA. One- and two-dimensional (2D) gel analyses combined with IgE immunoblotting and mass spectrometry [liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS)] were performed to detect IgE-reactive pollen components. RESULTS: Up to 16.7% of IgE reactivity to Japanese hop was inhibited by common hop. A 12-kDa protein component of Japanese hop pollen that showed the most potent IgE reaction was absent from common hop. Six IgE-reactive components from Japanese hop were detected by 2D gel electrophoresis and LC-ESI-MS/MS, but showed low Mascot scores, preventing positive identification. CONCLUSION: No significant IgE cross-reaction was observed for Japanese and common hop pollen allergens. Development of allergy diagnostic and immunotherapeutic reagents based on Japanese hop pollen are urgently needed.

Standardization of Weed Pollen Extracts, Japanese Hop and Mugwort, in Korea

PURPOSE: Japanese hop (Humulus spp.) and mugwort (Artemisia spp.) are notable causes of autumn pollinosis in East Asia. However, Japanese hop and mugwort pollen extracts, which are widely used for the diagnosis, have not been standardized. This study was performed to standardize Japanese hop and mugwort pollen extracts. MATERIALS AND METHODS: Allergen extracts were prepared in a standardized way using locally collected Humulus japonicus and purchased Artemisia vulgaris pollens. The immunoglobulin E (IgE) reactivities of prepared extracts were compared with commercial extracts via IgE immunoblotting and inhibition analyses. Intradermal skin tests were performed to determine the bioequivalent allergy unit (BAU). RESULTS: The IgE reactive components of the extracts via IgE immunoblotting were similar to those of commercial extracts. A 11-kDa allergen showed the strongest IgE reactivity in Japanese hop, as did a 28-kDa allergen in mugwort pollen extracts. Allergenic potencies of the investigatory Japanese hop and mugwort extracts were essentially indistinguishable from the commercial ones. Sums of erythema of 50 mm by the intradermal skin test (SigmaED50) were calculated to be 14.4th and 13.6th three-fold dilutions for Japanese hop and mugwort extracts, respectively. Therefore, the allergenic activity of the prepared extracts was 90827.4 BAU/mg for Japanese hop and 34412 BAU/mg for mugwort. CONCLUSION: We produced Japanese hop and mugwort pollen extracts using a standardized method. Standardized Japanese hop and mugwort pollen extracts will facilitate the production of improved diagnostic and immunotherapeutic reagents.

The Allergenic Potency of Japanese Hop Pollen Is Increasing With Environmental Changes in Korea

PURPOSE: The sensitization rate to Japanese Hop (Hop J) in respiratory allergy patients has increased in recent years in Korea. We evaluated changes in the allergenic potency of Hop J pollen collected in 1998 and 2009. METHODS: Thirty-five patients with allergic rhinitis and/or asthma were enrolled. Group I included 21 subjects sensitized to Hop J at an initial visit and group II included 14 subjects who developed a new sensitization. Hop J pollens were collected in 1998 and 2009 (98 and 09 extracts) and both urban and suburban environments (urban and suburban extracts). Serum specific IgE levels to Hop J pollen extracts were compared using an enzyme-linked immunosorbent assay (ELISA). IgE binding components were compared by IgE immunoblot analysis. RESULTS: Serum specific IgE levels to the 09 and urban extracts in both groups increased significantly compared to those of the 98 and suburban extracts. IgE immunoblot demonstrated that the major 10 kDa allergen was intensified in group I, while it was newly generated in group II with additional components ranging from 12-95 kDa. When the 98 and 09 extracts were compared, intensification of the major allergen of 09 extract had occurred in both groups. The IgE binding components of the urban extract was stronger than those of suburban one. CONCLUSIONS: The allergenic potency of Hop J pollen may be increased with environmental changes.