Allergenicity of recombinant profilins from Japanese hop, Humulus japonicus.

■ Abstract Background and objective: Pollen from Japanese hop, Humulus japonicus, is a major cause of pollinosis in Korea. Profi lin (15 kDa) from Humulus scandens has been associated with strong allergenicity in allergic Chinese patients. Profi lin has also been detected in pollen extract from Korean Japanese hop by proteomic analysis and immunoglobulin (Ig) E immunoblotting. However, the allergenicity of allergens isolated from Japanese hop has not been investigated in Korean individuals. This study was undertaken to produce recombinant profi lin from Japanese hop and evaluate its allergenicity. Methods: Complementary DNA sequences encoding 2 isoallergens were cloned by reverse transcription polymerase chain reaction and their recombinant proteins expressed in Escherichia coli. The IgE-binding reactivities of the recombinant allergens were assessed by enzymelinked immunosorbent assay. Results: The deduced amino acid sequences of the H japonicus profi lins were 68.7% to 80.2% homologous with profi lins from mugwort (Art v 4), ragweed (Amb a 14), and birch (Bet v 2). Two isoallergens of profi lin from H japonicus were 78.2% identical. Notably, the cDNA sequences of these 2 isoallergens were 98.5% (AY268422) and 98.7% (AY268424) identical to those of H scandens. Serum samples from Japanese hop–sensitized individuals showed 12.9% IgE reactivity to both of the recombinant profi lin isoallergens from H japonicus, indicating that profi lin may not be an allergenically dominant component of Japanese hop pollen. The recombinant profi lins showed only 0% to 9.3% inhibition of the crude extract. Conclusions: Two isoallergens of profi lin that are highly conserved with those of mugwort, ragweed, and birch were identifi ed in H japonicus. Profi lins from Japanese hop pollen may play a minor role in the pathogenesis of pollinosis in Koreans.