Whether to pollen, mould, dust, fungal spores or animal dander, all airborne allergies have the same root cause: the immune system responding inappropriately to a harmless substance, or allergen. How that inappropriate response develops is a matter of debate, but the results are predictably unpleasant.
Because airborne allergens are breathed in, they tend to hit the upper airways hardest. When a pollen grain lands on the damp lining of the nose and throat, its tough outer coat can burst, releasing its contents, including allergenic proteins. These come into contact with immune cells called mast cells, which are the body's first line of defence against invaders.
In most people, these harmless proteins are ignored, but those with allergies are not so lucky. Receptors on the surface of their mast cells bind to the offending proteins, prompting ...
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