ABSTRACT
In the diagnosis of human allergic disease in vitro laboratory tests for total IgE and specific IgE antibodies are often used when a patient’s clinical history identifies atopy and a relevant allergen exposure. This chapter discusses the various in vitro tests that are available, their interpretations and pitfalls. IgE is the least abundant isotype in the blood of normal, non-atopic individuals with typical levels of only 0.05% of the total immunoglobulin concentration. Total serum IgE levels are age-related. Shortly after the discovery of IgE, the radioallergosorbent test was introduced for the detection of allergen specific IgE in patient’s serum. Basophils present in the peripheral blood generally represent less than 1% of the total leukocyte population. The usefulness of in vitro Basophil Activation Test for the detection of allergen-induced expression of CD63 or the upregulation of CD203c has been demonstrated for various IgE-mediated allergies and is being investigated for its utility as a diagnostic tool.
