Asthma and allergy--disorders of civilization?

Abstract

There is both increasing public concern over the four subcategories on the basis of the timing and type (i.e. antibodyor cell-mediated) of immunolorising trends in allergic diseases, and continuing confusion over precisely what is covered by this gical response produced. Since most of the classical allergic responses fall into the first category of term in clinical practice. This review examines the cellular and mediator mechanisms involved in the immediate (or type 1) hypersensitivity, which differentiates them from those with a more gradual onset, most frequently encountered allergic disorders, especially those involving the respiratory mucous this review will focus on type I hypersensitivity. The range of diseases in which immediate-type hypermembrane. It stresses the importance of the environment and our effect thereon as a key factor in the sensitivity is involved is large. Most frequently, this type of allergic response occurs at a mucosal rising trends in both the developed and the developing world. surface, an important interface between the external environment and internal milieux. It gives rise to ‘Allergy’ is frequently used loosely to describe human intolerance to environmental factors. This such disorders as asthma, perennial and seasonal rhinitis (hay fever), allergic sinusitis, conjunctivitis broad use has included such diseases as migraine, irritable bowel syndrome, chronic fatigue syndrome and, in the gastrointestinal tract, food and drug reactions. In the skin, allergic (atopic) eczema and (ME) and, at the extreme end of the spectrum, a ‘total allergy syndrome’ (‘Allergy to the 20th urticaria (hives) represent two extremes of the Type 1 allergic response, the former being a chronic Century’). While a strong case can be made for the human body being intolerant to a wide variety of condition with quiet and active periods, the latter being of sudden onset but usually resolving rapidly. environmental pathogens and toxins, a more restricted use of the word allergy provides greater In the eye, allergic responses associated with allergic rhinitis or sensitization to cosmetics leads insight into one of the most exciting areas of modern medicine. Here, I will narrow C. Von Pirquet’s to an acute superficial conjunctivitis, while a more severe and intractable allergic response such as that original description of allergy (1906): ‘The ability of animals and humans to develop altered responses to encountered in vernal and giant papillary conjunctivitis may be sight-threatening through damage to foreign substances after repeated exposure’ to that of P.G. Gell and R.R. Coombes (1964): ‘Immune the cornea. One of the most dramatic manifestations of the immediate-type allergic response is anaphylresponses which give rise to irritant or harmful reactions’. A key feature of the allergic response is axis, in which body contact with minute amounts of the offending allergen (e.g. penicillin, bee venom the involvement of the immune system, which can be exquisitely sensitive to, and specific for, factors or peanuts) produces cardiovascular collapse, severe bronchoconstriction, urticaria and swelling of the in the modern environment. The classical work of Gell and Coombes1 divides mucous membranes (angioedema) which may require life-saving measures. To place these varied allergic responses or hypersensitivity reactions into