Investigators find more evidence to support IgE as a reliable biomarker for targeted biologic therapy in asthma management.
Lanny Rosenwasser, MD
The results of a recent study exploring the use of immunoglobulin E (IgE) as a biomarker in the diagnosis of asthma and find it to be a “reliable biomarker” that may aid in identifying asthma phenotype, choosing an appropriate therapeutic intervention, and determining patient improvement on therapy.
Uncontrolled asthma is one of the most common health issues that lead to health care provider and emergency room (ER) visits. According to recent National Ambulatory Medical Care Surveys, asthma events led to 1.3 million outpatient department visits, 10.5 million physician office visits, and 2 million ER visits in the United States in 2015. The economic impact of these events is staggering, with data from the US Centers for Disease Control and Prevention indicating that, in 2007, the total impact of medical costs and lost school and work days was $56 billion.
In order to stay ahead of the curve in asthma treatments, accurate diagnosis and outcome predictors are key. Biologic therapies may be one such approach to gain more precise asthma control.
Development of a biologic therapy involves identifying biomarkers that distinguish the disease and connect it with the most effective therapies. For asthma, the biomarkers that have been studied include blood eosinophils, exhaled nitric oxide, sputum eosinophils, and total and specific IgE.
Eosinophils are a type of white blood cell that fights infection in part by promoting inflammation. Eosinophilic asthma and allergic asthma are 2 phenotypes of asthma most commonly linked with elevated IgE. Eosinophilic asthma is associated with types of IgE; however, it is not associated with total IgE levels in all aspects of asthma. Allergic asthma, on the other hand, is linked with both total and specific IgE.
Total IgE can vary based on genetics, environment, location, and immune system status; but, in general, levels greater than 333 IU/mL are firmly associated with atopy in children 14 years and older. When total IgE is high, lung function decreases. Increased total IgE concentrations can pull eosinophils to the site of an allergen patch test and nonatopic controls who are given an atopic transfer serum or intradermal purified antibody experience the same result. This link has not been fully studied.
Specific IgE response is due to a suspected allergen, such as dust mites, and higher levels can be evidence of more exposure and sensitization; but, levels must be correlated with symptoms because a patient that is asymptomatic can have elevated specific IgE.
“IgE is an important biomarker for allergy, atopy [heightened allergen immune response], and allergic diseases, as well as type 2 immune response,” study author Lanny Rosenwasser, MD, professor of Pediatrics and Medicine at the University of Missouri-Kansas City School of Medicine told MD Magazine®. “Allergic asthma most closely associates with IgE, but severe allergic and non-allergic asthma can be associated with low IgE, and mild asthma can be associated with high IgE.”
Although IgE is not a good monitor of day-to-day asthma control, Rosenwasser adds, it can act as a marker of risk and the therapeutic implications are evident.
The study, “Immunoglobulin E as a Biomarker in Asthma,” was published online in Immunology and Allergy Clinics of North America.