 The primary purpose of this study is to identify additional mechanisms of action of omalizumab that will lead to improved stratification of patients for treatment. Understanding the response of specific innate immune effector cells in the lung can provide clues to these questions. Investigators will use non-invasive measures of a discrete cell population to examine the downstream effects of omalizumab treatment in the lung. Information derived from these studies will help clarify mechanisms of action of omalizumab and help identify potential tools for patient endotyping and stratification for therapeutic interventions. 