What type of hypersensitivity is involved in seasonal allergic conjunctivitis?

Seasonal allergic conjunctivitis is primarily associated with Type 1 hypersensitivity reactions. This type of hypersensitivity, also known as immediate hypersensitivity, is mediated by immunoglobulin E (IgE). When an individual who is sensitized to specific allergens, such as pollen or dust mites, is re-exposed to these allergens, the IgE antibodies bound to mast cells trigger the release of various mediators, including histamine. This leads to the characteristic symptoms of allergic conjunctivitis, such as itching, redness, and tearing of the eyes.

The rapid onset of symptoms following exposure to the allergen further exemplifies its classification as a Type 1 hypersensitivity reaction, as these reactions typically occur within minutes to hours after exposure. In summary, the involvement of IgE and mast cells in the allergic response is what delineates seasonal allergic conjunctivitis as a Type 1 hypersensitivity reaction.