Allergic inflammation immediate allergic reaction or as a Type I allergic reaction. The reaction is caused by the release of histamine and mast cell granule proteins by a process called degranulation, as well as the production of leukotrienes, prostaglandins and cytokines, by mast cells following the cross-linking of allergen specific IgE molecules bound to mast cell FcεRI receptors. These mediators affect nerve cells causing itching, smooth muscle cells causing contraction (leading to the airway narrowing seen in allergic asthma), goblet cells causing mucus production, and endothelial cells causing vasodilatation and edema. The late phase of a Type 1 reaction (which develops 8–12
Allergic conjunctivitis Horner-Trantas dots are specific features of vernal type. Giant papillary conjunctivitis is not a true ocular allergic reaction and is caused by repeated mechanical irritation of the conjunctiva. Repeated contact with the conjunctival surface caused by the use of contact lenses is associated with GPC. PKC results from a delayed hypersensitivity/inflammatory reaction to antigens expressed by various pathogens. Common agents include Staph. aureus, Mycobacterium tuberculosis, Chlamydia and Candida. A detailed history allows physicians to determine whether the presenting symptoms are due to an allergen or another source. Diagnostic tests such as conjunctival scrapings to look for eosinophils are helpful in