1. Department of Pathology, University of Zürich, CH-8091 Zürich, Switzerland.
2. Centre d'Immunologie INSERM-CNRS de Marseille-Luminy (CIML), Case 906, 13288 Marseille Cedex 9, France.
3. Preclinical Research, Sandoz Pharma, CH-4002 Basel, Switzerland.
4. Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka 565, Japan.