The role of IgE in the immunopathology of allergic disease has been well characterised. Essentially, it is able to sensitise mast cells in the skin and gut; through binding to a surface receptor molecule. Upon repeat exposure, allergens in direct contact with sensitised mast cells may cross-link the surface bound IgE molecules. This results in the release of mast cell derived inflammatory mediators such as histamine, proteases and prostaglandins. The pharmacological effect of these mediators on local tissue results in inflammation and the clinical signs of allergy. In serological testing the IgE antibody is used a diagnostic marker for environmental allergens.
The pathogenesis of AFRs is often uncertain, but may include IgE-meditated allergy, possibly IgG and also cell-mediated hypersensitivity. The latter cannot be tested for serologically, but specific cell-mediated hypersensitivity is likely, also to be reflected in an IgE or IgG response.
For this reason we offer both tests that we believe gives the best chance of identifying any possible involvement. However, neither test can be used to make a diagnosis, but rather to select the most appropriate diet for a hypoallergenic diet trial. Published studies have shown that these tests have a negative predictive value of .805 – that is to say they will identify the correct allergens for a diet trial in greater than 4/5 cases. (http://www.sciencedirect.com/science/article/pii/S0165242712000062)