Pollen Allergy; Mechanism and Etiology

The term allergy refers to an exaggerated immune response to a foreign molecule. In a normal healthy individual, this foreign molecule will act as a harmless antigen, as it will be recognized & cleared by the immune system without causing any significant damage to host tissues. In certain individuals, such antigens stimulate immune system in such a way that a series of exaggerated immune response are generated against it, leading to significant tissue injury and damage to the host. Such as exaggerated immune response may also cause death of the patient. Such antigen is termed as an allergen. Allergy is categorised under Immunoglobulin E (IgE) mediated type I hypersensitivity reactions. These reactions occur when an antigen acting as an allergen attacks the immune system of the host and causes excessive stimulation of mast cells and basophils. This is followed by the release of allergy mediators which are responsible for causing local or systemic anaphylaxis, allergic asthma, allergic rhinitis, conjuctivitis. Type I allergens are of various types, the mechanism of action is same; however underlying factors may differ in each type. This article is about pollen allergens, in specific & will discuss the common sources of pollen allergens in Pakistan, the relevance and the factors behind pollen allergy.