The discovery of IgE

In 1919, the search began for the factor, later called reagin, that could mediate an allergy, such as allergic asthma, in sera of allergic subjects. In 1967, the fifth class of immunoglobulins, IgE, was discovered and found to be able to carry reagin activity. This discovery has had immense importance for the understanding, diagnosis, and treatment of allergic diseases.