IgE immune response to Ginkgo biloba pollen

Background: The ginkgo (Ginkgo biloba L) continues to be planted as a shade tree in preference to other species in Seoul, Korea. The proportion of gin kgo to total shade trees was 43.2% in 1998, but the allergenic characterist ics of ginkgo pollen has not been elucidated. Objectives: This study was undertaken to obtain information regarding the s kin reactivity rate to ginkgo pollen in a population of Korean subjects wit h respiratory allergy. Possible ginkgo pollen allergens and the cross-react ivity of ginkgo pollen with other prevalent pollens were also examined. Methods: Four hundred and forty-seven patients with asthma and/or allergic rhinitis were skin prick tested with extract of ginkgo pollen (1:20 wt/vol) . Of these patients, positive skin responders (AM ratio greater than or equ al to2+) were selected for ELISA and immunoblot experiments. Results: A total of 21 patients (4.7%) showed skin reactivity (A/H ratio gr eater than or equal to2+) to ginkgo pollen in the skin prick test. They wer e also cosensitized to many other tree, grass, and weed pollens. Sixteen (7 6%) of the 21 positive skin responders showed specific IgE responses to gin kgo pollen in ELISA. In inhibitory ELISA, IgE binding to ginkgo pollen was inhibited by more than 80% by oak, ryegrass, mugwort, and ragweed; and 34% by hop Japanese; and 10% by rBet v 2 at 10 mug/mL. In immunoblot, 10 out of 21 sera (48%) reacted to the 15-kD protein of ginkgo pollen, 9 (43%) to 33 -35 kD, and 8 (38%) to 36-38 kD. In inhibitory immunoblot, IgE binding to g inkgo pollen proteins was almost completely inhibited by oak, ryegrass, mug wort and ragweed, but only partially by hop Japanese and rBet v 2. Conclusion: The skin reactivity rate to ginkgo pollen is approximately 4.7% in a population of Korean subjects with respiratory allergy. Since ginkgo pollen has a high cross-reactivity with other prevalent pollens, it could c ause clinical symptoms during its pollen season by cross-reacting with the IgE produced in response to other pollens in patients sensitized to multipl e pollens.