Kiwi allergens and their cross-reactivity with birch, rye, timothy, and mugwort pollen

In order to study kiwi allergens and examine their cross-reactivity to birch, rye, timothy, and mugwort pollen, immunoblot and enzyme immunoassay (EIA) inhibition tests were performed with self-prepared kiwi extract. For the investigations, the sera of 22 kiwi-allergic patients were used, which were characterized by radioallergosorbent (RAST) measurements for kiwi, birch pollen, and apple with commercial allergen disks. The RAST values for kiwi were compared with those obtained by self-prepared kiwi extract disks. In the RAST, the allergen potency of this extract was found to be very similar to that of the commercial extracts. This extract was able to bind immunoglobulin E from kiwi-allergic patients in the immunoblots and EIA. Immunoblot results revealed a broad spectrum of IgE specificities; 12 allergens were identified within the range of 15 to 94 kDa, 10 of which cross-reacted with birch, timothy, rye, and mugwort pollen, while two (25 and 30 kDa) were not inhibited homologously or by pollen. EIA inhibition additionally revealed kiwi-specific allergens. Three proteins of the kiwi extract (25, 30 and 43 kDa) were considered to contain a carbohydrate moiety. Profilin seems to be relevant in cross-reactivity of kiwi allergens.