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Occupational asthma due to IgE mediated allergy to the flower Molucella laevis (Bells of Ireland)
  1. W M A J Miesen1,
  2. S van der Heide1,
  3. H A M Kerstjens2,
  4. A E J Dubois1,
  5. J G R de Monchy1
  1. 1Department of Allergology, Clinic for Internal Medicine, Groningen University Hospital, Groningen, Netherlands
  2. 2Department of Pulmonology, Clinic for Internal Medicine, Groningen University Hospital
  1. Correspondence to:
 Dr W M A J Miesen, University Hospital Groningen, Hanzeplein 1, PO Box 30001, 9700 RB Groningen, Netherlands; 


Background: About 25% of greenhouse flower and/or ornamental plant growers sensitised to workplace flowers or moulds have occupational asthma, a disease that is suffered by 8% of the growers who cultivate these crops.

Aim: To document a case of occupational asthma due to IgE mediated allergy to the flower Molucella laevis.

Methods and Results: There was a history of work related seasonal asthmatic and rhinoconjunctivitis symptoms in a Molucella laevis grower. Bronchial obstruction following exposure to Molucella laevis was documented by a fall in FEV1 from 89% to 73% of predicted during seasonal exposure to Molucella laevis. Daily PEF measurements showed a fall from 500 to 250 l/min during this period following withdrawal of inhaled steroids. Bronchial reactivity to inhaled methacholine was increased (PC20 1.45 mg/ml). Confirmation of sensitisation to Molucella laevis flower pollen extract was done using an SPT and by demonstration of Molucella laevis specific serum IgE (18 IU/ml; class 4). Specific inhalation challenge with Molucella laevis extract provoked an early and late asthmatic reaction (EAR and LAR) with a fall in FEV1 compared with control day of 40% and 53% respectively, with associated 5.1-fold increase in absolute sputum eosinophil cell counts and 2.9-fold increase in neutrophil cell counts.

  • occupational allergy
  • asthma
  • flower
  • rhinitis
  • EAR, early asthmatic response
  • FEV1, forced expiratory volume in 1 second
  • HEP, histamine equivalent prick test
  • LAR, late asthmatic response
  • OA, occupational asthma
  • PEF, peak expiratory flow
  • SPT, skin prick test

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