Why Dr. William Shaw recommends total IgG food allergy testing instead of only IgG4
Food allergy is common among children with neuropsychiatric conditions such as autism, Tourette syndrome, and OCD. Laboratory results that can help parents pinpoint which foods are causing reactions are valuable tools. In his article on the Great Plains Laboratory website, Dr. Shaw explains why testing only for IgG4, which is commonly recommended, is not sufficient when looking at food allergy.
He says: “In IgG mediated food allergy testing, the goal is to identify foods that are capable of causing inflammation that can trigger a large number of adverse reactions. IgG1, IgG2, and IgG3 all are capable of causing inflammation because these antibodies do not exchange heavy and light chains with other antibodies to form bispecific antibodies. Thus, IgG1, IgG2, and IgG3 antibodies to food antigens can and do form large immune complexes or lattices that fix complement and increase infl ammation. The presence of IgG4 antibodies to food antigens indicates the presence of antibodies to foods that will not usually cause inflammation even though high amounts of these antibodies do indicate the presence of immune reactions against food antigens. Testing only for IgG4 antibodies in foods limits the ability of the clinician to determine those foods that are causing significant clinical reactions that are affecting their patients.”
Excerpted from Great Plains Laboratory website