Background: A recent study of subjects with peanut allergy treated with omalizumab generated some results that were concordant with a study of subjects with cat allergy treated with omalizumab. However, there were differences that provided additional insight into the nature of the cellular responses in allergic subjects.
Objective: We sought to determine the cause for failure to suppress the allergen-induced basophil response during treatment with omalizumab.
Methods: Patients with peanut allergy were treated with omalizumab. Clinical, serologic, and cellular indices relevant to the response of the subjects and their peripheral blood basophil values (specific/total IgE ratio, cell-surface FcεRI expression, and histamine release responses to anti-IgE antibody or peanut allergen) were obtained at 3 times.
Results: After treatment, approximately 60% of the subjects' basophil responses to peanut allergen did not significantly decrease. In 40% of cases, the in vitro basophil response to peanut allergen increased 2- to 7-fold. The increases were associated with 2 primary factors: a high (>10%) specific/total IgE ratio and an increase in the intrinsic response of the basophil to IgE-mediated stimulation. The extent to which the basophil response to peanut allergen increased was inversely correlated with improvement in the patient's ability to tolerate ingestion of peanut.
Conclusion: The basophil response during treatment with omalizumab is a consequence of 2 competing factors: suppression of allergen-specific IgE on the cell surface versus increased intrinsic sensitivity to IgE-mediated stimulation. In subjects with peanut allergy, the basophil response appears to mitigate against the ability of omalizumab to improve the patient's tolerance of oral allergen.
Copyright © 2012 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.