To investigate the role of indoor allergens in adult patients with acute asthma, we conducted a case-controlled study on patients presenting to an emergency room. One hundred and fourteen patients and 114 control subjects were enrolled over a 1-yr period in Wilmington, Delaware. Sera were assayed for total IgE, and for IgE antibodies to dust mites, cat dander, cockroach, grass pollen, and ragweed pollen. Dust was obtained from 186 homes and assayed for dust mite, cat, and cockroach allergens. IgE antibodies to mite, cat, and cockroach were each significantly associated with asthma, and this association was very strong among participants without medical insurance and among African Americans. Among 99 uninsured participants, sensitization to one of the indoor allergens (> 200 RAST units) was present in 28 of 57 asthmatics and in one of 42 control subjects (odds ratio, 39; confidence interval, 9.4 to 166). For cat and cockroach the combination of sensitization and presence of allergen in the house was significantly associated with asthma. Furthermore, there was a strong inverse relationship between IgE antibodies to cat and to cockroach, and the risk of this sensitization was in large part restricted to homes or areas with high levels of allergen. Thirty-eight percent of the asthmatics, but only 8% of the control subjects, were allergic to one of the three indoor allergens, and had high levels of the relevant allergen in their houses (odds ratio, 7.4; confidence interval, 3.3 to 16.5). The results suggest that the risk for asthma related to sensitization to indoor allergens applies to a large proportion of adults with acute asthma and that this risk is prominent among the socioeconomic groups that have suffered the largest increase in both morbidity and mortality from asthma.

Type I allergy is an immunoglobulin E (IgE)‐mediated hypersensitivity disease affecting more than 25% of the population. Currently, diagnosis of allergy is performed by provocation testing and IgE serology using allergen extracts. This process defines allergen‐containing sources but cannot identify the disease‐eliciting allergenic molecules. We have applied microarray technology to develop a miniaturized allergy test containing 94 purified allergen molecules that represent the most common allergen sources. The allergen microarray allows the determination and monitoring of allergic patients’ IgE reactivity profiles to large numbers of disease‐causing allergens by using single measurements and minute amounts of serum. This method may change established practice in allergy diagnosis, prevention, and therapy. In addition, microarrayed antigens may be applied to the diagnosis of autoimmune and infectious diseases.

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE‐mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE‐mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well‐defined, highly pure molecules for component‐resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the “EAACI Molecular Allergology User's Guide” (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state‐of‐the‐art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.