Institute of Immunology, University of Rostock, Schillingallee 70, D-18057 Rostock, Germany. serrano@pzr.uni-rostock.de|Institute of Immunology, University of Rostock, Schillingallee 70, D-18057 Rostock, Germany. serrano@pzr.uni-rostock.de|Institute of Immunology, University of Rostock, Schillingallee 70, D-18057 Rostock, Germany. serrano@pzr.uni-rostock.de|Institute of Immunology, University of Rostock, Schillingallee 70, D-18057 Rostock, Germany. serrano@pzr.uni-rostock.de|Institute of Immunology, University of Rostock, Schillingallee 70, D-18057 Rostock, Germany. serrano@pzr.uni-rostock.de