Paradoxical Serologic Observation in an ABPA patient treated with Omalizumab
Published Online: October 24, 2013
Allergic Bronchopulmonary Aspergillosis (ABPA) is an inflammatory respiratory condition, associated with recurrent exacerbations, which can lead to bronchiectasis and/or extensive fibrosis. The primary treatment for ABPA is oral steroids. When steroids fail or side effects are significant, alternative therapeutic modalities are limited. Omalizumab, a monoclonal antibody directed against IgE, has been employed in select patients with anecdotal success. As omalizumab binds free IgE, total IgE is anticipated to significantly rise after its administration.
In a recent article published in The Journal of Allergy and Clinical Immunology: In Practice, Wolf et al. report a case study of an elderly ABPA patient followed over four years. The patient experienced multiple relapses and hospitalizations despite repeated and extended use of steroids and courses of anti-fungal antibiotics. Cognitive side effects of steroids became intolerable leading to a trial of omalizumab. On omalizumab, over the first ten months, the patient’s pulmonary functions remained stable and his daily steroid dosage requirement dropped 85%. Total IgE, measured by the Immunocap assay, had been tracked in this ABPA patient prior to use of omalizumab. Total IgE was expected to rise but instead dramatically decreased >50% immediately following omalizumab administration and remained near or lower than its previously recognized nadir over the following ten months.
This case is an outlier since the limited number of ABPA patients treated with omalizumab reported in the literature exhibited little or no decrease in total IgE. IgE is accepted as the marker to follow longitudinally in ABPA to monitor for disease (re)activity. This patient’s precipitous fall in total IgE was an unexpected but desired serologic outcome. Questions arise as to the mechanism(s) of this observation and how to follow an ABPA patient whose IgE may be dampened or masked by omalizumab.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.