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Context: Seasonal allergic rhinitis is a common IgE-mediated disorder that produces troublesome symptoms. A recombinant humanized monoclonal anti-IgE antibody (omalizumab) forms complexes with free IgE, blocking its interaction with mast cells and basophils and lowering free IgE levels in the circulation.Objective: To assess the efficacy and safety of omalizumab for prophylaxis of symptoms in patients with seasonal allergic rhinitis.Design: Randomized, double-blind, dose-ranging, placebo-controlled trial conducted from July 25 through November 21, 1997.Setting: Twenty-five outpatient centers throughout the United States.Patients: Five hundred thirty-six patients aged 12 to 75 years with at least a 2-year history of moderate to severe ragweed-induced seasonal allergic rhinitis and a baseline IgE level between 30 and 700 IU/mL.Interventions: Patients were randomly assigned to receive omalizumab, 50 mg (n = 137), 150 mg (n = 134), or 300 mg (n = 129), or placebo (n = 136) subcutaneously just prior to ragweed season and repeated during the pollen season every 3 weeks in patients with baseline IgE levels of 151 to 700 IU/mL (4 total treatments) and every 4 weeks in patients with baseline IgE levels of 30 to 150 IU/mL (3 total treatments).Main Outcome Measures: Self-assessed daily nasal symptom severity scores (range, 0-3), rescue antihistamine use, and rhinitis-specific quality of life during the 12 weeks from the start of treatment.Results: Nasal symptom severity scores were significantly lower in patients who received 300 mg of omalizumab than in those who received placebo (least squares means, 0.75 vs 0.98, respectively; P =.002). A significant association was observed between IgE reduction and nasal symptoms and rescue antihistamine use. Rhinitis-specific quality of life scores were consistently better in patients who received 300 mg of omalizumab than in those who received lower dosages or placebo and did not decline during peak season. The frequency of adverse events was not significantly different among the omalizumab and placebo groups.Conclusion: Omalizumab decreased serum free IgE levels and provided clinical benefit in a dose-dependent fashion in patients with seasonal allergic rhinitis. [ABSTRACT FROM AUTHOR]

To differentiate the diagnoses of exercise-induced anaphylaxis and cholinergic urticaria/anaphylaxis, we developed reproducible diagnostic provocative challenges. The data derived from the study of two representative patients, one with cholinergic urticaria and the other with exercise-induced anaphylaxis, suggest approaches to distinguishing these diagnoses. After specific exercise challenges, both patients developed symptoms consistent with anaphylaxis and had associated increases in plasma histamine levels. After passive heat challenges inducing increases in core body temperature more than 0.7 degrees C, only the patient with cholinergic urticaria developed anaphylactic symptoms and had a rise in the plasma histamine level. Neither patient developed symptoms of anaphylaxis when core body temperatures were increased after administration of intravenous endotoxin. Thus, passive heat challenges are extremely valuable in differentiating these two exercise-related syndromes. Although not important in exercise-induced anaphylaxis, specific thermoregulatory mechanisms appear to play an intricate part in the pathophysiology of cholinergic urticaria/anaphylaxis.

We report two cases of recurrent episodes of hoarseness, cough, flushing, pruritus, and rash occurring within 30 minutes of topical exposure to carbonless copy paper. Provocative challenges revealed that alkylphenol novolac resin was the ingredient responsible. Video endoscopy of the larynx was performed and plasma histamine levels were obtained prior to and 30 minutes after cutaneous challenge of a patient with alkylphenol novolac resin. We documented marked laryngeal edema and a sixfold increase in plasma histamine levels after challenge. We conclude that topical exposure to carbonless copy paper may cause mast cell/basophil-mediated acute systemic and potentially life-threatening reactions in susceptible patients.