Assessment of Cellular Antigen Stimulation Test in Diagnosis of Drug Allergy

Diagnosis of the etiology of drug hypersensitivity is a vital step in therapy, which is mainly done through patient history, as skin testing is not always reliable and oral provocation testing is life-threatening. Cellular Antigen Stimulation Test (CAST) is a test, based on the determination of sulfidoleukotrienes produced by basophiles stimulated by allergens in vitro, has been proposed. Our objective was to evaluate the efficacy of Cellular Antigen Stimulation Test in diagnosis of patients with history of allergy to drugs and compare values with healthy controls. The study included 45 patients with drug allergy and 45 healthy persons as control group, both were subjected to full detailed allergic history to drugs and clinical examination, Skin prick test and Patch test to the particular drug were performed . Serum specific IgE of the drug, CAST by Enzyme Linked Immunoassay were also done. The sensitivity of CAST in drug allergy was 48.9% and the specificity was 84.4%. Skin prick test, Patch test and specific IgE sensitivity in allergic patients were 51.1%, 33.3%, 62.2%, while their specificity were 91.1%, 91.1% and 73.3% respectively. CAST has relatively higher specificity than sensitivity in diagnosing drug allergy. The value of this test is important specially when other in vitro or in vivo diagnostic tests are not reliable, as well as in non-IgE mediated hypersensitivity reactions.