All statistical analyses were performed with Stata statistical software (release 14.0, StataCorp). Results Demographic characteristics of the study population, including reported symptoms and sensitization to cat and dog extracts Baseline characteristics were similar between the children included in the study and children in the original cohort (see Table E1 in this articles Online Repository at www.jacionline.org). or dog was a better longitudinal predictor of cat or dog symptoms than X-Gluc Dicyclohexylamine results of IgE tests with cat or dog allergen extract, respectively. Cross-sectionally, cat/dog-polysensitized children had higher IgE levels and more frequent symptoms to cat and dog X-Gluc Dicyclohexylamine than monosensitized children. Conclusions Sensitization to Fel d 1 and Can f 1 in childhood and polysensitization to either cat or dog allergen molecules predict cat and dog allergy cross-sectionally and longitudinally significantly better than IgE to cat or dog extract. and dogs allergen Can f 1, together with Can f 2, Can f 4, and Can f 6, belongs to the lipocalin family. Can f 3, a serum albumin, and Can f 4 have been reported to be allergens of less importance.14,15 Can f 5, a prostatic kallikrein in male dog urine, has recently been reported to be recognized by up to 70% of dog-sensitized patients.14,16 More knowledge is needed in the area of pet allergy, where the X-Gluc Dicyclohexylamine clinical history often is inconclusive X-Gluc Dicyclohexylamine and many patients are polysensitized to several furry animals, such as cat, dog, and horse. Furthermore, some allergen molecules might be poorly represented in crude allergen extracts,17 leading to uncertain results. However, molecular allergy diagnostics allow for an increased accuracy in allergy diagnosis and prognosis and are able to reveal the specific pet allergen molecules responsible for sensitization and symptoms.18 The aims of the present study, which is part of the European UnionCfunded project Mechanisms for the Development of Allergy (MeDALL; http://medall-fp7.eu/)19 program, were (1) to investigate IgE reactivity to individual cat and dog allergen molecules in childhood through adolescence for the first time by using the BAMSE birth cohort, (2) compare the results with cat and dog extract IgE levels, (3) identify risk markers in preschool- and school-aged children for allergic symptoms to cat and dog up to the age of 16 years, and (4) assess the phenotypes of monosensitized and polysensitized subjects to cat and dog allergens. Methods Study cohort The BAMSE study is an unselected population-based birth cohort study of 4089 children.20,21 For this study, data from baseline and the 4-, 8-, and 16-year follow-ups, the time points when blood was drawn, were used in conjunction with serologic allergy testing. At the respective follow-ups, sera were available for 64%, 60%, and 62% of the population. Background data were retrieved from the baseline questionnaire. Reported respiratory symptoms at pet exposure were obtained from the questionnaires at 4, 8, and 16 years of age. Symptoms to cat and dog were defined as reported symptoms from the upper airways, lower airways, or both at exposure to cat/dog (for definitions of symptoms, see the Methods section in this articles Online Repository at www.jacionline.org). For 1699 (42%) children, blood samples were obtained IFNA17 from the same children at each of the 3 time points of clinical follow-up (4, 8, and 16 years). A subset of 798 children was randomly picked by using the Stata software randomization function (StataCorp, College Station, Tex), providing 2394 (3 798) serum samples for analysis. Complete data on reported airway symptoms to cat and dog were available in 779 of these children, which constitute our study population. Permission for the study was obtained X-Gluc Dicyclohexylamine from the Regional Ethical Review board at Karolinska Institutet at each follow-up, and parents of participating children/children themselves (when applicable) provided informed consent. Allergen-specific IgE measurement Serum samples were initially tested with ImmunoCAP (Thermo Fisher AB, Uppsala, Sweden).
