IGG4 (IMMUNOGLOBULIN G SUBTYPE 4): is a very unique antibody. For example, when a patient does desensitization injections or sublingual therapy, the intent of therapy is not to decrease IgE, but to increase IgG4. When a patient says, “I used to be allergic to a certain food, but I grew out of it,” this means that they developed IgG4 antibodies, which block IgE reactions. IgG4 is a small antibody, different than IgG1, IgG2, and IgG3. It does not bind to complement as other IgG antibodies do, and is, therefore, unable to create inflammation in the same way. If you make more IgG4 than IgE, you will block the ability of IgE to bind to immune cells and prevent the release of histamine. In general, IgG4 antibodies are protective against allergies. On your report, if IgG4 is greater than IgE, this will be labeled as an immune tolerance to the food, indicated by the “yes” listed under Tolerance to IgE/Allergic reactions, on the first page of test results. This means your patient does not need to avoid these foods.
Too much IgG4 causes immune-mediated conditions, known as IgG4-RD that typically affects multiple organ systems in the body. For these reasons, it’s important to know the levels of IgG4 in the body to be able to maintain a correct balance. An example of a tissue that is susceptible to higher levels of IgG4 is the esophagus, resulting in Eosinophilic Esophagitis. IgG4 also interferes with the thyroid, contributing to autoimmune thyroiditis, and can also cause IgG4- Related Diseases (IgG4-RD) of the ovaries and prostate. If the patient has a condition in which IgG4 is deleterious, then they should remove these foods triggering the reaction. If they do not, then it is not necessary to take them out.
– Dr. Cheryl Burdette, ND.