Overview of 'allergy and allergic diseases: with a view to the future'.

Abstract

Allergic rhinitis, asthma and atopic eczema are among the commonest causes of chronic ill-health. These allergic diseases are increasing in prevalence and they add considerably to the burden of health-care costs. For example, in Sweden the number of children with allergic rhinitis, asthma or eczema roughly doubled over a 12 year period1, and in the US the annual cost of treating asthma is about $6 billion 2. The term 'allergy' was introduced in 1906 by Von Pirquet3, who recognized that in both protective immunity and hypersensitivity reactions the antigen had induced 'changed reactivity'. With the passage of time, the word allergy has become corrupted and is now frequently used synonymously with IgE-mediated allergic disease. This restricted meaning was not as von Pirquet originally intended. He proposed that the term should apply to the 'uncommitted' biological response which in the individual may lead either to immunity (which is beneficial) or allergic disease (which is harmful). As discussed by Dr Ewan (p 1087), allergists deal with the common allergic diseases that produce sneezing, wheezing, itching and digestive disorders. Most of their work involves the diagnosis and treatment of seasonal allergic conjunctivorhinitis ('summer hay fever'), perennial allergic rhinitis, allergic asthma (including occupational asthma), allergy to stinging insects (notably wasps and bees), food anaphylaxis and intolerance, allergy to drugs and allergy-related skin disorders like urticaria, angioedema and atopic eczema. The term atopy from the Greek atopos, meaning 'out of place' is often used when describing IgE-mediated diseases. Thus, atopic individuals have an hereditary predisposition to produce IgE antibodies against common environmental allergens and have clinical manifestations of one, or more, atopic diseases (i.e. allergic rhinitis, asthma and atopic eczema). Some allergic diseases (e.g. contact dermatitis and hypersensitivity pneumonitis) operate through IgE-independent mechanisms and in this sense can be considered as non-atopic, allergic conditions. This issue reviews the cellular and molecular basis of atopic allergy, the diseases with which it is associated, and certain approaches to treatment.