A 35-year-old man asks for advice regarding seasonal eye itching and runny nose. Recurrent conjunctivitis in this patient is most likely caused by which of the following mechanisms of disease?

Hypersensitivity. Although the incorrect choices may cause eye irritation, seasonal conjunctivitis is typically caused by allergies to pollens that are released during a particular time of the year. Allergic rhinitis (hay fever) is the most common type I hypersensitivity disease in adults. It may be caused by pollen, house dust, animal dandruff, and many other allergens. Antigens inhaled react with the IgE attached to basophils in the nasal mucosa, thereby triggering the release of vasoactive substances stored in cytoplasmic granules. Histamine, the main mediator released from mast cells, increases the permeability of mucosal vessels, causing edema and sneezing.Diagnosis: Conjunctivitis, hypersensitivity reaction