Which immunoglobulin plays a role in hypersensitivity?

The immunoglobulin that plays a crucial role in hypersensitivity is IgE. This type of antibody is primarily associated with allergic reactions and is responsible for mediating responses to allergens. When an individual who has been sensitized to an allergen is exposed to that allergen again, IgE antibodies bind to the allergen, which triggers the activation of mast cells and basophils. This process leads to the release of histamine and other inflammatory mediators, resulting in the symptoms commonly associated with allergic reactions, such as itching, swelling, and bronchoconstriction.

In contrast, other immunoglobulins like IgA are mainly involved in mucosal immunity, providing defense at mucosal surfaces. IgD plays a role in B cell activation and is not directly involved in hypersensitivity. IgG is the most abundant antibody in the bloodstream and is primarily responsible for long-term immunity and recognition of pathogens, contributing to neutralization and opsonization but not specifically linked to the mechanisms of hypersensitivity reactions.