RESEARCH LETTERS 137 this group. Although rare, anaphylactic reactions to PPIs have been described. 1---7 They have modified benzimidazoles with a pyridine ring and chemically related structures A number of case reports suggesting cross-reactivity patterns among lansopra- zole and rabeprazole, 2,3 omeprazole and lansoprazole, 4---6 and omeprazole and pantoprazole 1,4 have been reported. Our patient had IgE-mediated anaphylactic or urticarial reactions to lansoprazole, which were confirmed by her his- tory and positive SPT results. However, SPT and IDT were negative for other PPIs including, omeprazole, pantopra- zole, esomeprazole and rabeprazole. In addition, the oral challenge test showed that our patient tolerated therapeu- tic doses of omeprazole, pantoprazole, esomeprazole and rabeprazole. Vovolis reported IgE mediated allergic reac- tion to rabeprazole with good tolerance to omeprazole and lansoprazole. 7 To the best of our knowledge, our patient is the first reported case of anaphylaxis induced by lansopra- zole with good tolerance to other PPIs including rabeprazole. In conclusion, cross-reactivity between PPIs is conflicting. We also showed that controlled oral chal- lenge test using PPIs for which the SPT is negative is a safe approach to choose an alternative drug. References 1. Lobera T, Navarro B, Del Pozo MD, González I, Blasco A, Escud- ero R, et al. Nine cases of omeprazole allergy: cross-reactivity between proton pump inhibitors. J Investig Allergol Clin Immunol. 2009;19:57---60. 2. Porcel S, Rodríguez A, Jiménez S, Alvarado M, Hernández J. Allergy to lansoprazole: study of cross-reactivity among proton- pump inhibitors. Allergy. 2005;60:1087---8. 3. Pérez Pimiento AJ, Prieto Lastra L, Rodríguez Cabreros MI, González Sánchez LA, Rodríguez Mosquera M, Cubero AG. Hypersensitivity to lansoprazole and rabeprazole with toler- ance to other proton pump inhibitors. J Allergy Clin Immunol. 2006;117:707---8. 4. González P, Soriano V, López P, Niveiro E. Anaphylaxis to proton pump inhibitors. Allergol et Immunopathol. 2002;30:342---3. 5. Natsch S, Vinks MH, Voogt AK, Mees EB, Meyboom RH. Anaphy- lactic reactions to proton-pump inhibitors. Ann Pharmacother. 2000;34:474---6. 6. Galindo PA, Borja J, Feo F, Gómez E, García R, Cabrera M, et al. Anaphylaxis to omeprazole. Ann Allergy Asthma Immunol. 1999;82:52---4. 7. Vovolis V, Christogianni K, Koutsostathis N. Immunoglobulin E- mediated anaphylaxis to rabeprazole. J Investig Allergol Clin Immunol. 2010;20:360---1. E. Karabacak ∗ , A. Kutlu, E. Aydin, S. Ozturk GATA Haydarpasa Teaching Hospital, Istanbul, Turkey ∗ Corresponding author. E-mail address: ekarabacak@gata.edu.tr (E. Karabacak). http://dx.doi.org/10.1016/j.aller.2012.03.007 Cystic fibrosis and atopy To the Editor, Cystic fibrosis (CF) is the most common autosomal recessive disorder in Caucasians (1:2500---1:10,000 live newborns). The genetic defect of CF results from abnormalities of chromosome 7 that causes dysfunction in cystic fibrosis transmembrane conductance regulator (CFTR), a protein that regulates chlorine ion transport. It results in mucus thickness and reduction of mucociliary clearance, predis- posing the patient to inflammation and colonisation by Staphylococcus aureus and Pseudomonas aeruginosa. Coex- istence of allergy, as well as genetic and environmental factors may influence the phenotype of CF. Rhinosinusitis is frequent in CF and causes serious anatomic alterations in the sinus, although few patients spontaneously report symp- toms, often underestimated in comparison with the severity of the pulmonary disease. 1 Cystic fibrosis and asthma are not always easily distin- guished from each other. 2 Wheeze, whether in asthmatic or CF patients, is a result of airway obstruction due to inflammation, bronchospasm and retained secretions. Both diseases may coexist in the same patient, and poor lung function and bronchial hyper- responsiveness are common to both. 3 Bronchodilator response may be found in CF and demon- strates that this medication may help to alleviate the airflow limitation. Eosinophilia and high serum IgE leves are of limited value but personal and family history of atopy may be helpful. 3 Since 1 in 20 of the population are CF mutation carriers and have CFTR protein dysfunction, this would contribute to allergy in the community. In earlier study 47% of cystic fibrosis heterozygotes had positive prick skin tests to one or more antigens and 53% had histories of allergic disease, both occurring significantly more frequent than in a control group. 4 A cross-sectional study of 55 CF adult patients with upper and lower airway disease demonstrated that allergen spe- cific IgE was present to at least one aeroallergen in 67% by skin prick testing and 80% by RAST. Rhinitis occurred in 50% of the population with no detectable difference in lung function between those with and without allergic sen- sitisation. The authors concluded that individuals with CF should be evaluated for coexistent allergy and this warrants appropriate therapy. The rate of allergy to Aspergillus in this study was much lower than that reported in studies of chil- dren and adolescents with CF. These differences could be explained by the methods of detecting Aspergillus specific IgE, potency of allergenic extracts, degree of environmental exposure to Aspergillus, prevalence of allergic disease and IgE sensitisation to moulds in general population. 5 The frequent evidence of allergy could be explained by abnormalities in epithelial barrier function and mucus hypersecretion leading to retention of allergens in the respi- ratory tract with progressive exposure and sensitisation. Alternatively, a genetic predisposition to allergy has been