title: Cat sensitization identified by recombinant Fel d 1 several years before symptoms--results from the BAMSE cohort.
abstract: Exposure to cat is one of the most important causes of allergic disease. The objective of this study was to investigate IgE reactivity to the recombinant major cat allergen, rFel d 1, as an early marker of cat sensitization. Based on questionnaires, 144 children with allergic symptoms due to cat, or where such symptoms were suspected, were selected from the birth cohort BAMSE and allocated into three study groups. Blood samples taken at age 4 and 8 yrs were analysed for IgE to rFel d 1 and cat dander extract (CDE) by quantitative ELISA (cut-off limit 0.037 kU(A)/l) and the ImmunoCAP System (cut-off limit 0.35 kU(A)/l), respectively. At 4 yrs, 25/33 children with certain allergic symptoms to cat had IgE to both rFel d 1 and CDE, while 14/42 of those suspecting symptoms at 4 had IgE to rFel d 1 and 9/42 to CDE. In a group developing symptoms after 4 yrs, 60/69 had IgE to rFel d 1 and 57/69 to CDE at 8, while 33/69 had IgE to rFel d 1 already at 4 and 26/69 to CDE. This was the only one of the three study groups where a significant increase in the IgE levels to rFel d 1 was found from 4 to 8 yrs (p < 0.001), even when only children with IgE to rFel d 1 already at 4 were included (p < 0.001). We show that the single major cat allergen rFel d 1 is at least as good as CDE in the diagnosis of cat allergy in childhood. With a sensitive rFel d 1 assay cat sensitization can be detected several years before symptoms to cat are reported.
authors.affiliation: Department of Medicine, Clinical Immunology and Allergy Unit, Karolinska Institutet and University Hospital, Stockholm, Sweden.
authors.forename: Tiiu
authors.initials: T
authors.lastname: Saarne
authors.forename: Hans
authors.initials: H
authors.lastname: Grönlund
authors.forename: Inger
authors.initials: I
authors.lastname: Kull
authors.forename: Catarina
authors.initials: C
authors.lastname: Almqvist
authors.forename: Magnus
authors.initials: M
authors.lastname: Wickman
authors.forename: Marianne
authors.initials: M
authors.lastname: van Hage
mesh_terms: D000818:Animals; D002415:Cats / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood*; D008297:Male; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D006023:Glycoproteins; D011994:Recombinant Proteins; D007073:Immunoglobulin E; C059296:Fel d 1 protein, Felis domesticus