1. Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Box 7011, SE-750 07 Uppsala, Sweden
2. Department of Cell and Molecular Biology, Uppsala University, The Biomedical Centre, Box 590, SE-751 23 Uppsala, Sweden
3. Department of Immunology, Genetics and Pathology, Uppsala University, The Rudbeck Laboratory, SE-751 85 Uppsala, Sweden