Being an immunological disease, the characteristics of allergy are those of speci-city and memory. Regardless of whether the clinical manifestation is rhinoconjunctivitis, rhinitis, or asthma, the underlying immunological disorder is based on the adverse reactions of cells in the immune system upon contact with allergens. These cells are speci c for epitopes that are structural parts of allergens present in the allergenic source material. Two types of cells (i.e., Tcells and B-cells) produce receptor molecules (i.e., T-cell receptors and immunoglobulin [IgE] antibodies) that, through high-af nity interactions with the allergen, ef ciently catalyze the presence of even minute amounts of allergens into
life-threatening to the patient.