Which immunoglobulin is primarily responsible for allergic reactions?

The immunoglobulin primarily responsible for allergic reactions is immunoglobulin E (IgE). IgE plays a crucial role in the immune system by mediating hypersensitivity reactions. When an individual is exposed to an allergen, such as pollen or pet dander, IgE binds to the allergen and triggers a cascade of immune responses. This process involves the activation of mast cells and basophils, which release histamines and other inflammatory mediators. The release of these substances results in the typical symptoms of an allergic reaction, such as sneezing, itching, and swelling.

In contrast, other immunoglobulins have different roles in the immune system. Immunoglobulin M (IgM) is primarily involved in the initial response to an infection and in forming complexes that activate the complement system. Immunoglobulin G (IgG) is the most abundant antibody in serum and is responsible for long-term immunity and opsonization of pathogens. Immunoglobulin A (IgA) is found mainly in mucosal areas, such as the intestines and respiratory tract, protecting these surfaces from infection. Each type of immunoglobulin has its specific functions, with IgE being uniquely associated with allergic responses.