Unexpected decrease in total IgE in a patient with allergic bronchopulmonary aspergillosis treated with omalizumab

The algorithm of clinical treatment starts with high-dose tapering oral steroids and may require chronic steroid use and/or antifungal (azole) therapy.1 Omalizumab, a monoclonal anti-IgE that the US Food and Drug Administration indicated for the treatment of moderate-to-severe persistent allergic asthma, has also been used to treat other IgE mediated diseases, including ABPA.2,3 Dosing of omalizumab is based on a nomogram that factors baseline total IgE and a patient's weight in kilograms.4 A now 80-year-old, 66-kg man presented to us 3 years ago with lifelong cough and chest congestion, and a history of recent hospitalization for right and possible bilateral lower lobe pneumonia. The number of IgE receptors parallels the amount of free IgE. [...]by binding free IgE, omalizumab downregulates the expression of FC[straight epsilon]R1 receptors (and low affinity FC[straight epsilon]RII receptors) on dendritic or antigen-presenting cells (APC), basophils, and mast cells.