ABSTRACT
TINA K. HATLEY, JUDITH A. WOODFOLK, GEORGE A. WARD, Jr. and THOMAS A. E. PLATTS-MILLS
University of Virginia Health Sciences System Charlottesville, Virginia
I. Introduction
Asthma is an inflammatory disease of the lower airways in which common inhaled allergens, occupational agents, and viral and fungal elements, individually or in combination, play roles (1±6). The final common pathway is inflammation, bronchial hyperreactivity, and the well-known symptoms of airway obstruction (Fig. 1). The increase in mortality in some groups, and particularly among patients living in poverty in the United States, suggests that the severity of asthma and the prevalence have both increased. The persistent high prevalence and severity of asthma presents a challenge both to understanding the causes and to developing new modalities for treatment. Given the evidence for eosinophil-rich inflammation of the bronchi, it is logical to investigate patients to try to identify the antigens stimulating this immune response. However, it is clear that a large proportion of cases of severe asthma in adults do not have an obvious extrinsic (i.e., inhaled) cause for their disease. There are many other possible sources of foreign antigens, including colonizing organisms, viruses, and food, which have not been systematically investigated. The causes of extrinsic asthma have been more clearly defined, and it has become possible to focus on the patients among whom other causes of an inflammatory response of the bronchi should be investigated (7).
