IgE does not fix complement and is typically found in allergic individuals.

IgE does not fix complement and is typically found in allergic individuals.

• A. IgE fixes complement.
• B. IgE is heat stable.
• C. IgE attaches to tissue mast cells.
• D. IgE is found in serum of allergic individuals.

Answer: (C)

IgE’s role is to arm tissue mast cells and basophils for a rapid allergic reaction. Its Fc region binds to high-affinity receptors on these cells (FcεRI). When an allergen cross-links the IgE molecules that are bound on a mast cell, it triggers degranulation and release of histamine and other mediators, causing the allergic response. This is why IgE attached to tissue mast cells is the best description of its action in allergic individuals. IgE does not fix complement, because its structure and Fc region do not activate the classical complement pathway the way IgM or IgG can. While IgE can be present in serum, in allergic people most of it is actually bound to mast cells in tissues, so its functional effect is tied to these sensitized cells rather than just circulating in the blood.

IgE’s role is to arm tissue mast cells and basophils for a rapid allergic reaction. Its Fc region binds to high-affinity receptors on these cells (FcεRI). When an allergen cross-links the IgE molecules that are bound on a mast cell, it triggers degranulation and release of histamine and other mediators, causing the allergic response. This is why IgE attached to tissue mast cells is the best description of its action in allergic individuals.

IgE does not fix complement, because its structure and Fc region do not activate the classical complement pathway the way IgM or IgG can. While IgE can be present in serum, in allergic people most of it is actually bound to mast cells in tissues, so its functional effect is tied to these sensitized cells rather than just circulating in the blood.