IGHE and Allergy: ,4,10 Conversely, levels of total IgE (tIgE) alone are considered useless as standalone in the diagnosis of specific allergies; however, the proportion of sIgE to tIgE, known as IgE SA, which reflects the proportion of IgE bound to effector cells that is specific for a given allergen, may be more informative.11, 12, 13 An individual’s reactivity to allergen is likely affected by the proportion of non-sIgE and its occupation of high affinity IgE receptors (FcεRI) on the surface of effector cells.11