Which immunoglobulin is responsible for activating mast cells in an allergic response?

The immunoglobulin responsible for activating mast cells in an allergic response is IgE. This antibody plays a crucial role in the body's immune response to allergens. When an allergen is encountered, IgE binds to its specific antigen and then attaches to mast cells and basophils, which are types of white blood cells involved in allergic reactions. This binding process sensitizes the mast cells.

Upon subsequent exposure to the same allergen, the allergen cross-links the IgE molecules on the surface of the mast cells, triggering them to degranulate. This degranulation releases various mediators such as histamine, leukotrienes, and prostaglandins, leading to the symptoms associated with allergic reactions, such as inflammation, itching, and bronchoconstriction.

In contrast, other immunoglobulins listed do not have the same role in allergic responses. IgA mainly functions in mucosal immunity, providing a first line of defense in areas such as the respiratory and gastrointestinal tracts. IgM is the primary antibody produced during the initial immune response and is effective in agglutinating pathogens but not specific to mast cell activation in allergies. IgG is responsible for various immune functions, including neutralization of toxins and opsonization,