ABSTRACT
INTRODUCTION Nasal allergy and nasal irritation are two phenomena that are frequently confused by both clinicians and toxicologists alike. Classical “allergy” (as in rhinitis and asthma) is an antibody (IgE)-mediated immediate hypersensitivity response to allergens, the vast majority of which are high molecular weight and biological in origin (1). “Irritation,” on the other hand, can be defined variously as chemically induced tissue damage, subjective irritation of the airway, skin, or mucous membranes, stimulation of nociceptive nerves, reflex changes triggered by such nerve stimulation, or a combination of these effects (2-4). On an inflammatory level, allergic conditions are generally associated with allergen-induced mast cell activation and TH2 (T-helper lymphocyte, type 2 differentiation) lymphocyte and eosinophil infiltration, whereas pathologic chemical irritation is generally marked by polymorphonuclear leukocyte influx (similar to bacterial or viral infection). Allergy is further defined clinically by the presence of circulating allergen-specific IgE antibodies and/or a wheal-and-flare reaction after epicutaneous presentation of an allergen during skin testing, the result of in vivo mast cell activation through allergen/IgE interaction (5).
