1. From the Institute of Immunology, Rikshospitalet, University of Oslo, N-0027 Oslo, Norway
2. Department of Molecular Biology, Odense University, DK-5230 Odense M, Denmark
3. Department of Immunohaematology and Blood Bank, Leiden University Hospital, 2300 RC Leiden, The Netherlands
4. Department of Gastroenterology, Ullevaal Hospital, 0407 Oslo, Norway