Pathogenic mechanisms: a rational basis for treatmentBMJ 1998; 316 doi: http://dx.doi.org/10.1136/bmj.316.7133.758 (Published 07 March 1998) Cite this as: BMJ 1998;316:758
- Peter H Howarth
Allergic diseases such as asthma, rhinitis, eczema, and anaphylaxis are increasingly common and, in addition to being associated with morbidity and potential mortality, constitute a considerable burden on health resources, with both direct and indirect costs. This article discusses the pathogenic mechanism underlying the clinical signs and symptoms of these diseases and explains the basis for the choice of differing treatments.
Relation of atopy and allergy to disease
About 40% of the population is atopic as evidenced by a positive response to a skin prick test with an allergen, but not all show signs and symptoms of clinical disease. There may be a latency period, as students who have positive skin prick tests with grass pollen but who do not experience hay fever have been shown to go on to develop seasonal allergic rhinitis. A threshold response may also be required for signs and symptoms of clinical disease to develop, as allergic airway inflammation is present in the lower airways of patients with perennial allergic rhinitis sensitive to house dust mite who do not have clinical asthma. This inflammatory response falls between the response in patients with clinical asthma and that in non-atopic healthy controls.
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