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Characterization of recombinant cat albumin


Rudolf Valenta, MD, Molecular Immunopathology Group, Department of Pathophysiology, Vienna General Hospital, University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria. E-mail:


Background  Indoor allergens derived from animals and mites often contribute to exacerbation of skin manifestations in atopic dermatitis (AD) patients.

Objective  To produce and characterize recombinant cat albumin, a cross-reactive animal allergen.

Methods  A complete cDNA coding for cat albumin was obtained by RT-PCR amplification from cat liver RNA. Recombinant cat albumin was expressed in Escherichia coli as hexahistidine-tagged protein, purified by nickel affinity chromatography and studied for IgE reactivity with sera from cat-allergic patients by ELISA and immunoblotting. Furthermore, CD203c expression of basophils from cat-allergic patients upon exposure to recombinant cat albumin was analysed.

Results  Recombinant cat albumin, a cross-reactive animal allergen sharing most IgE epitopes with its natural counterpart, was produced in E. coli. It was recognized preferentially by IgE from AD patients and elicited IgE-dependent basophil activation in sensitized patients.

Conclusions  Recombinant cat albumin may be used as a paradigmatic tool to analyse mechanisms of allergen-triggered exacerbation of AD, for diagnostic and, perhaps for therapeutic purposes.