Immune monitoring for precision medicine in allergy and asthma

•New methods are revealing previously unknown heterogeneity of immune cells.•There is a need to compare immune monitoring results in blood versus sites of disease.•Immune monitoring may improve allergy diagnosis and the safety and efficacy of treatment.•Immune monitoring may enable tailored immunotherapy for individual patients.•Data derived from immune monitoring studies in large diverse populations will inform efforts to consider developing a new taxonomy of allergic diseases. ‘Precision Medicine’ embodies the analyses of extensive data collected from patients and their environments to identify and apply patient-specific prophylactic strategies and medical treatments to improve clinical outcomes and healthcare cost-effectiveness. Many new methods have been developed for evaluating the activity of the human immune system. Such ‘immune monitoring’ approaches are now being used in studies of allergy and asthma in the hope of identifying better correlates of disease status, predictors of therapeutic outcomes, and potential side-effects of treatment. Together with analyses of family histories, genetic and other biometric data, and measurements of exposures to environmental and other risk factors for developing or exacerbating disease, immune monitoring approaches promise to enable ‘Precision Medicine’ for allergic diseases and asthma.