The immune system of allergy affected individuals, for reasons not fully understood, misinterprets a usually innocuous substance as a disease agent and begins producing a type of antibody against it, called immunoglobulin E (IgE). This is called the 'primary antibody response.' The IgE produced during this response binds to basophils in the bloodstream and to a similar type of cell called mast cells in the tissues. When the person again encounters the allergen, it binds to the IgE that has already attached to basophils and mast cells, causing release of histamine, prostaglandins, and leukotrienes, producing inflammation of the surrounding tissues, and bringing about the familiar allergic symptoms.But on occasion, IgG immunoglobulin can itself activate the mast cells and basophils:
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part of the therapeutic mechanism relies on the preferential induction of allergen-specific IgG to neutralize the allergen in place of allergen-specific IgE.
The immune system normally protects us by making antibodies against foreign invaders such as bacteria and viruses. These antibodies are called IgG and are often referred to as gammaglobulins. Usually, IgG is not formed to any normal body tissue but occasionally, by error, this does happen. If antibody binds to normal tissues it can cause damage to the body or create other disease symptoms. Rheumatoid arthritis is a good example of an autoimmune disease. Antibodies that react with body tissues are felt to contribute to joint swelling and pain. Many other common diseases are caused by autoimmunity such as juvenile diabetes and low thyroid disease.In your case, I'd guess that the allergy shots induced not only an IgG antibody to the thing you're allergic to (the allergen) but also another IgG antibody that binds to the active region of the first IgG antibody and the IgE antibody that also binds to the allergen.
It has been recently discovered that some persons who suffer with hives or angioedema also have an autoimmune disease. In these cases, autoantibodies have been formed that bind to the Fc-receptor on mast cells. The normal function of the Fc-receptor is to anchor allergic antibodies, called IgE, to the mast cell surface (see the mast cell diagram below). IgE is formed in allergic persons and binds specifically to allergens in the environment. When airborne allergens land on nasal tissues or eye conjunctiva, or are eaten (foods) and enter the body through the intestinal tract they bind to the specific IgE. As a result of this interaction, a signal is sent by the IgE antibody to the mast cell causing it to release its histamine. Histamine release causes the nasal and eye symptoms seen in those who suffer with "hay fever" and can produce hives, angioedema, or even life-threatening symptoms such as respiratory compromise or low blood pressure.
In persons with autoimmune hives, the IgG autoantibody that binds to the Fc-receptor tricks the mast cell into believing that the IgE on its surface has encountered an allergen. When this happens, hives or tissue swelling can result. (The diagram above shows a Mast cell with purple histamine granules. The "patient IgG" is the autoantibody that binds to the Fc-receptor.)
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Also, is the advising doctor in this case the same one administering the allergy shots?
posted by elizardbits at 12:55 PM on November 26, 2012 [4 favorites]