Higher immunoglobulin E antibody levels to recombinant Fel d 1 in cat-allergic children with asthma compared with rhinoconjunctivitis

Clin Exp Allergy. 2008 Aug;38(8):1275-81. doi: 10.1111/j.1365-2222.2008.03003.x. Epub 2008 May 12.


Background: Current diagnosis of allergy and asthma to cat is confirmed using cat dander extract (CDE). We have previously engineered a recombinant major cat allergen, rFel d 1, with properties identical to the natural molecule.

Objective: The aim of the study was to evaluate IgE and IgG4 antibodies to rFel d 1 among sera from cat-allergic children and adults suffering from asthma and/or rhinoconjunctivitis (RC) in populations from Sweden and Austria.

Methods: Cat-allergic children and adults from Sweden (n=27 and 31, respectively) and Austria (n=41 and 41) with RC and/or asthma were selected. Sera were tested for IgE and IgG4 antibodies to CDE and rFel d 1 by CAP, and IgE to rFel d 1 by ELISA. Healthy subjects and non-cat-allergic patients (n=75) were included as controls.

Results: There was a high correlation between IgE responses to rFel d 1 and CDE among the 140 patients (r(s)=0.85, P<0.001); however, measured levels to rFel d 1 were on average 30% higher (P<0.0001). Ninety-eight percent of patients and none of the controls showed IgE to rFel d 1 and there was a threefold increased risk of asthma for half of the children with the highest IgE levels [odds ratio 3.23; 95% confidence interval (CI), 1.19-8.79] by ELISA. IgE responses to rFel d 1 among children with asthma were higher (median 19.4 kU/L) compared with children with RC (median 6.6 kU/L, P<0.05) and adults with asthma (median 3.0 kU/L, P<0.01). Furthermore, children with asthma displayed higher IgG4 levels than the asthmatic adults.

Conclusion: A single recombinant molecule, rFel d 1, is at least as sensitive for in vitro diagnostics of cat allergy as the current extract-based test. Elevated IgE antibody levels to Fel d 1 are suggested to be a risk factor for asthma in cat-allergic children.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Asthma / diagnosis*
  • Asthma / immunology
  • Cats / immunology
  • Child
  • Child, Preschool
  • Conjunctivitis, Allergic / diagnosis
  • Conjunctivitis, Allergic / immunology*
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Glycoproteins / immunology*
  • Humans
  • Immunoglobulin E / blood*
  • Immunoglobulin E / immunology
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • Male
  • Radioallergosorbent Test
  • Recombinant Proteins / immunology
  • Rhinitis, Allergic, Perennial / diagnosis
  • Rhinitis, Allergic, Perennial / immunology*
  • Sensitivity and Specificity


  • Glycoproteins
  • Immunoglobulin G
  • Recombinant Proteins
  • Immunoglobulin E
  • Fel d 1 protein, Felis domesticus