Which immunoglobulin class is typically found at elevated levels in allergic individuals?

Which immunoglobulin class is typically found at elevated levels in allergic individuals?

• A. IgA
• B. IgG
• C. IgE
• D. IgM

Answer: (C)

Allergic reactions are driven by IgE antibodies. In atopy, Th2 responses produce IL-4 and IL-13, which push B cells to switch from making IgM or IgG to producing IgE. This IgE binds to high-affinity receptors on mast cells and basophils. When the allergen is encountered again, it cross-links the bound IgE, triggering degranulation and release of histamine and other mediators that cause allergy symptoms. Because of this mechanism, total IgE levels are often elevated in allergic individuals, and specific IgE against particular allergens indicates sensitization. Other immunoglobulins serve different roles—IgA is mainly mucosal, IgG is the main circulating antibody with broad opsonization functions, and IgM is the first responder in new infections—so they aren’t the hallmark elevated in allergy.

Allergic reactions are driven by IgE antibodies. In atopy, Th2 responses produce IL-4 and IL-13, which push B cells to switch from making IgM or IgG to producing IgE. This IgE binds to high-affinity receptors on mast cells and basophils. When the allergen is encountered again, it cross-links the bound IgE, triggering degranulation and release of histamine and other mediators that cause allergy symptoms. Because of this mechanism, total IgE levels are often elevated in allergic individuals, and specific IgE against particular allergens indicates sensitization. Other immunoglobulins serve different roles—IgA is mainly mucosal, IgG is the main circulating antibody with broad opsonization functions, and IgM is the first responder in new infections—so they aren’t the hallmark elevated in allergy.