IgE antibodies are the primary antibodies responsible for allergic reactions. Each allergic substance, known as an allergen, causes the production of a specific IgE antibody to that substance. Depending on the individual, different substances will cause the immune system to react differently.
During an allergic reaction, where the immune system feels the body is being threatened by the presence of a specific substance, that substance or allergen stimulates the production and release of the IgE antibodies. When the amount of antibody present becomes overwhelming, these cells burst and release histamines into the body through the surrounding tissue and blood stream. Histamine is what causes the common allergy symptoms such as sneezing, runny nose, itchy eyes, rashes, hives, gastrointestinal discomfort, constriction of the throat, headaches, joint pain and others.
Each individual has his or her own threshold for the amount of histamine release s/he can tolerate before the allergy symptoms occur.
The symptoms often occur fairly soon after exposure and can stay present for some time afterwards because the mast cells may have been stimulated enough upon exposure to continue making the antibody for some time afterwards.