Immune Hypersensitivity Reactions
Two of the antibodies involved in an allergic reaction are immunoglobulins E (IgE) and immunoglobulin G (IgG). IgE production occurs right after ingestion or inhalation of an allergy and is referred to as a Type I Immediate Hypersensitivity Reaction. Type I reactions are usually seen in acute allergies like hives, sneezing, itchy eyes and a runny nose. IgG antibodies are produced for several hours or days after exposure to an allergen are called Type III Delayed Hypersensitivity Reactions. There are several subclasses of IgG ranging from IgG1 – IgG4. IgG1 is believed to be the main inflammatory component however; IgG4 induces histamine release which triggers food allergies. The IgG Allergy – Blood Spot Test measures total IgG subclasses 1, 2, 3 and 4.
IgG Delayed Onset Allergies
In a Type III delayed hypersensitivity reaction, IgG forms an immune complex with the allergen / antigen. This is called an IgG-Ag complex. This complex activates as series of biochemical pathways which trigger the release of inflammatory mediators into the body. Wherever the immune complex is deposited in the body is where the symptoms begin. This is why food sensitivities can appear in many areas of the body aside from the digestive system where the allergen originated from. This process can take anywhere from several hours to several days which is why hypersensitivy reactions are delayed. Immune cells of the body called macrophages act like “mops” and pick up the IgG-Ag complexes immediately for disposal. However, they have limited capacity to do so especially if the body is saturated with IgG-Ag complexes causing excessive deposition into tissues. Depending on which tissues are involved, deposition of these IgG-Ag complexes may result in the following:
|Vascular Tissue||headaches, vasculitis, hypersensitivity|
|Respiratory Tissue||asthma, alveolitis, recurrent infections|
|Skin Tissue||eczema, psoriasis, hives and other dermatological conditions|
|Joint Tissues||rheumatoid arthritis, rheumatism, joint pains|
|Sinus Tissues||sinusitis, rhinitis, angioedema, post nasal drip, excess mucous|
|Digestive Tissues||inflammatory bowel disease, irritable bowel symptoms|
|Urinary Tissues||interstitial cystitis, frequent bladder infections, irritable bladder|
|Nervous Tissue||attention deficit hyperactive disorder, irritability, nervousness|
|Endocrine Tissue||thyroid problems and other hormonal imbalances|
IgG allergies are difficult to diagnose because reactions do not occur until hours or days after ingestion of an allergen. This makes it extremely difficult to determine which foods are causative agents. Blood spot testing for IgG provides a simple and practical means for me to uncover potential causes of allergic reactions and allergy related disease.