Allergy

Abstract

Although the immune mechanism protects the host from a hostile environment by such means as destroying invading organisms and rejecting foreign cells and tissues, the immune response may also cause tissue damage and untoward symptoms in the host. Allergies are diseases which are mediated by such maladaptive immune responses. Each of these conditions has its genesis in the ingestion, inhalation, or absorption through the skin of a substance which is perceived by the body as foreign. An immune response is generated which results in the clinical manifestations of allergy, its form varying from one disease to another. It is important to identify the kind of immune response which mediates each allergy since successful treatment depends upon knowledge of the pathogenic mechanism. These tissue damaging reactions have been categorized by Gell and Coombs (10) into four categories.