What is Immuglobulin E?

A.  A class of proteins manufactured by specialized immune cells that help to deactivate invading organisms that cause disease.

B.  Any substance that stimulates the production of antibodies.

C.  An antigen that produces allergic reactions.

The correct answer is (A) – A class of proteins manufactured by specialized immune cells that help to deactivate invading organisms that cause disease.  One of five classes of immunoglobulins made by humans (the others being IgA, IgD, IgG and IgM).  The main function seems to be to protect the host against invading parasites. While parasitic disease may not be a major clinical issue in most industrialized nations, it is a major public health problem in developing nations. The antigen-specific IgE interacts with mast cells and eosinophils to protect the host against the invading parasite. However, the same antibody-cell combination is also responsible for typical allergy or immediate hypersensitivity reactions such as hay fever, asthma, hives and anaphylaxis.