1. ¹Department of Dermatology, Division of Immunology, Allergy and Infectious Diseases (DIAID), Medical University of Vienna, Vienna, Austria
2. ²Research Center for Molecular Medicine of the Austrian Academy of Sciences (CeMM), Vienna, Austria
3. ³Division of Immunopathology, Department of Pathophysiology, Center for Physiology and Pathophysiology, Medical University of Vienna, Vienna, Austria

Correspondence: Dr Georg Stingl, Department of Dermatology, Division of Immunology, Allergy and Infectious Diseases (DIAID), Medical University of Vienna (MUW), Währinger Gürtel 18-20, Vienna A-1090, Austria. E-mail: georg.stingl@meduniwien.ac.at

Received 30 May 2007; Revised 20 November 2007; Accepted 31 January 2008; Published online 15 May 2008.

Abstract

Previous studies have shown that sera of patients with severe atopic dermatitis (AD) contain IgE specific for self-proteins, supporting the hypothesis of autoreactivity as a pathogenic factor in AD. In this study, we screened a large panel of AD patients (n=192) by western blotting (WB) for IgE reactivity not only against the human epithelial cell line A431 but also against primary keratinocytes (KCs). To investigate autoantigenic cell structures in detail, normal human skin and primary KCs were incubated with sera from both WB-reactive patients and, for control purposes, healthy individuals, and analyzed by immunohistology, confocal laser microscopy, and flow cytometry. Our analysis revealed that 28% of AD patients, but not healthy individuals, display serum IgE autoreactivity by WB analysis. The individual IgE reaction patterns of the sera pointed to the existence of unique as well as common specificities against epidermal or A431-derived proteins. Immunostainings identified cytoplasmic and, occasionally, also cell membrane-associated moieties as targets for autoreactive IgE antibodies. Interestingly, in certain autoreactive patients, the surface-staining pattern was accentuated at cellular contact sites. We conclude that IgE autoreactivity is common, particularly among severe AD patients, and that non-transformed primary cells are needed for characterization of the entire spectrum of IgE-defined autoantigens.