1. Biozentrum of the University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
2. Instituto de Investigaciones Biomedicas, 28029 Madrid, Spain
3. Philipps-Universität Marburg, Robert-Koch-Str. 17, 35037 Marburg, Germany
4. Department of Immunoregulation, Research Institute of Microbial Diseases, Osaka University, Osaka 565, Japan