Mercurialis annua pollen: a new source of allergic sensitization and respiratory disease

Sensitization to Mercurialis annua pollen in 13 patients admitted for allergy study of asthma, rhinitis, or rhinoconjunctivitis is described. Twelve of these patients were also sensitized to other common aeroallergens. In five patients, a relationship was found between exposure to M. annua pollen and elicitation of symptoms. All patients were prick test and RAST positive to an extract of M. annua pollen. Nasal provocation test proved positive in 10 of 12 patients, and bronchial provocation test was positive in the only patient in whom it was performed. Two late responses were recorded. Immunoblotting of the 13 sera revealed two different groups of relevant allergens; one of isoelectric point 10.2, reacting with 12 of the 13 sera, and the other allergen of isoelectric point 5.0 to 5.5, reacting with 11 of the 13 sera. M. annua pollen is able to induce both sensitization and clinical disease in atopic patients. Since sensitization to this pollen accounts for 8.5% of total positive skin tested patients in the same period, we believe M. annua pollen should be considered as a relevant allergen and thus included in skin test batteries. Some patients labeled as having "intrinsic" asthma or rhinitis might be sensitized to this and other previously unknown allergens.