Bee Pollen-Induced Anaphylaxis: A Case Report and Literature Review.

Bee pollen is pollen granules packed by honey bees and is widely consumed as natural healthy supplements. Bee pollen-induced anaphylaxis has rarely been reported, and its allergenic components have never been studied. A 40-year-old male came to the emergency room with generalized urticaria, facial edema, dyspnea, nausea, vomiting, abdominal pain, and diarrhea 1 hour after ingesting one tablespoon of bee pollen. Oxygen saturation was 91%. His symptoms resolved after injection of epinephrine, chlorpheniramine, and dexamethasone. He had seasonal allergic rhinitis in autumn. Microscopic examination of the bee pollen revealed Japanese hop, chrysanthemum, ragweed, and dandelion pollens. Skin-prick with bee pollen extracts showed positive reactions at 0.1 mg/mL (A/H ratio > 3+). Serum specific IgE to ragweed was 25.2, chrysanthemum 20.6, and dandelion 11.4 kU/L; however, Japanese hop, honey-bee venom and yellow-jacket venom were negative (UniCAP®, Thermo Fisher Scientific, Uppsala, Sweden). Enzyme-linked immunosorbent assay (ELISA) confirmed serum specific IgE to bee-pollen extracts, and an ELISA inhibition assay for evaluation of cross-allergenicity of bee pollen and other weed pollens showed more than 90% of inhibition with chrysanthemum and dandelion and ~40% inhibition with ragweed at a concentration of 1 μg/mL. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and IgE-immunoblot analysis revealed 9 protein bands (11, 14, 17, 28, 34, 45, 52, 72, and 90 kDa) and strong IgE binding at 28-34 kDa, 45 and 52 kDa. In conclusion, healthcare providers should be aware of the potential risk of severe allergic reactions upon ingestion of bee pollen, especially in patients with pollen allergy.