EFFECT OF OMALIZUMAB ON VENOM SPECIFIC IGE AND VENOM SKIN TESTING

Abstract

<h3>Introduction</h3> Omalizumab, a monoclonal IgG antibody which binds free IgE, is indicated for the treatment of chronic spontaneous urticaria, uncontrolled nasal polyps, and moderate to severe asthma with perennial allergic sensitization. This case illustrates the effect of omalizumab on venom-specific IgE and percutaneous testing. <h3>Case Description</h3> A 48 year old female with severe persistent asthma on omalizumab for six years experienced wheezing and throat swelling within two hours of a suspected hymenoptera sting. Evaluation while patient remained on omalizumab included venom serology obtained two weeks after sting, which was positive only to paper wasp and white-faced hornet, and percutaneous testing three months after sting to honeybee, yellow jacket, and yellow hornet, which was negative through 0.1 ug/mL intradermals, at which time testing was stopped due to systemic reaction. After holding omalizumab for sixteen weeks, repeat percutaneous testing was performed but confounded by dermatographism; repeat venom serology revealed increased specific IgE to all tested hymenoptera except honeybee. <h3>Discussion</h3> To our knowledge, this is the first report describing omalizumab's effect on venom-specific IgE levels and percutaneous testing. Given previous studies that have suggested omalizumab does not convert specific IgE for environmental allergens from positive to negative, it is important for allergists to be aware of omalizumab's potential to suppress venom-specific IgE and skin test reactivity. If a patient on omalizumab with concern for venom hypersensitivity has negative serologic or percutaneous testing to hymenoptera, consideration should be given to repeating testing after omalizumab has been discontinued for four to five half-lives.