Allergens are antigens
reacting with specifi c IgE antibodies. Allergens originate from a wide range of
mites, animals, insects, plants, fungi or are small molecular weight chemicals.
They are usually classifi ed as indoor allergens (mites, some moulds, animal
danders, insects) or outdoor allergens (pollens and some moulds). The role
of allergens in the development of asthma is well established (314), although
some uncertainties remain (37). Exposure to allergens is a trigger for
symptoms in sensitized individuals with asthma. This is especially true for