ABSTRACT
The history of allergens dates back to 1873, when Charles Blackley showed that pollen grains were able to induce symptoms of hay fever and that aqueous pollen extracts gave rise to immediate wheal and flare reactions when scratched into the skin of a hay fever patient (himself).1 During the 1920s, it was appreciated that inhalation of allergens from pollens, house dust, or animals, or ingestion of allergens in foods was associated with clinical symptoms of hay fever, asthma, atopic dermatitis or food allergy, and that these conditions affected 10-20% of the population. In the 1960s, the first allergens were purified and biochemically characterized from ragweed and rye grass pollens,2,3
and the landmark studies by the Ishizakas revealed that immediate hypersensitivity reactions were mediated by a new class of antibody, termed immunoglobulin E (IgE). During the 1960s and the 1970s, many allergens were purified; however, it was difficult to establish the nature of some of these molecules. In 1980, the house dust mite major allergen Der p 1 was
be concentrated in mite fecal particles.4,5
Allergens from mites and other natural sources have since been identified, including cockroach allergens Bla g 1 and Bla g 2, and fungal allergens from Alternaria, Aspergillus, and Trichophyton.6-9 By the mid-1980s a large number of allergens had been purified using biochemical techniques, but in general the yields were poor and, apart from physicochemical properties, the molecular structures of these proteins were ill defined.
