1. Department of Molecular Medicine II , Medical Faculty, Heinrich Heine University , Universitätsstr. 1 , D-40225 Düsseldorf , Germany
2. School of Medicine , University of Central Lancashire , Preston , PR1 2HE , UK
3. Department of Biochemistry and Molecular Biology II , Medical Faculty , Universitätsstr. 1 , D-40225 Düsseldorf , Germany
4. Institute of Immunology , Medical Faculty, University of Duisburg-Essen , Hufelandstr. 55 , D-45147 Essen , Germany