If you use the phrase “I break out in hives just thinking about trigonometry”, that cliché reflects a psychosomatic response to something you intensely dislike. Now, if you truly break out in hives after a bee sting, you are having an immunological and physiological response to something your body cannot tolerate. The antigen – a bee sting – triggered an acute allergic response from your IgE antibodies. You’ll note, however, that bee sting did not produce reactions from your other antibodies of IgA, IgD, IgG or IgM. Let’s explore this in terms of food sensitivities and intolerance as compared to food allergies. First, here’s a refresher course about antibodies.
An antibody (Ab), also known as an immunoglobulin (Ig), is a protein produced by plasma cells that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes an unique part of the foreign target, called an antigen (Ag).
Antibodies can come in different varieties known as classes. In mammals, there are five antibody types known as IgA, IgD, IgE, IgG, and IgM, each of which are expressed differently in the body.
- IgA – Found in and on mucosal surfaces, such as the gut, respiratory tract and urogenital tract. Also found in saliva, tears, sweat, and breast milk.
- IgD – Functions mainly as an antigen receptor on B-cells (circulating or humoral immune cells) that have not been exposed to antigens.
- IgE – Binds to allergens (allergy-creating proteins) and triggers histamine release from tissue mast cells and basophils (a specialized white blood cell), and so is involved in allergic responses.
- IgG – In its four forms, provides the majority of long term circulating antibody-based immunity against invading organisms. It is also the antibody capable of crossing the uterine placenta to give passive immunity to the fetus.
- IgM – Expressed on the surface of B cells, like IgD, and then multiplies 4-fold and is secreted. Constitutes the primary immune response for several months until IgG takes over for the long term.
Type I Hypersensitivity Reaction: Mediated by IgE and IgG
Food and other true allergies produce an immediate, immune response that is sometimes life-threatening. A good example is anaphylactic shock, which causes the airway to close and the inability to breathe. Rashes, hives and swollen eyes are examples of less severe, but also serious, allergic responses. They show up in the blood as antigens to IgE and eventually to IgG.
Type II and Type III Hypersensitivity Reactions: Mediated by IgA and IgM
Food intolerances/sensitivities are typically chronic conditions that build up over time—perhaps after months or even years of exposure to the offending foods. It is estimated from professional experience, that food sensitivities are at least 10 to 15 times more common than food allergies.
Food intolerances/sensitivities are caused by Types II and III hypersensitivity reactions, which show up in saliva or feces as antigens to IgA and IgM. Although they are generally not life-threatening, these reactions to food can affect many different aspects of an individual’s physical and emotional well-being.
Common signs include:
• GI tract issues similar to IBD (“leaky gut”)
• Chronic itching
• Chronic burping and gas rumblings (borborigmi)
• Chronic skin, ear and foot infections (especially with the presence of yeast)
NutriScan, developed exclusively for companion animals, measures IgA and IgM antibodies in the saliva of dogs and cats. By detecting elevated IgA and IgM antibody levels to certain foods, NutriScan identifies specific food ingredient(s) causing the clinical problem. NutriScan can also differentiate between the more common food intolerance/sensitivity and the more rare food allergy, because food allergies are typically mediated by different antibodies (IgE and IgG) than food intolerances/sensitivities (IgA and IgM).