1. Biomedical Research Institute Georg-Speyer-Haus, 60596 Frankfurt, Germany.
2. Division of Immunology/Hematology/BMT, Children's Research Center (CRC), University Children's Hospital Zürich, CH-8032 Zürich, Switzerland.
3. Division of Surgical Research, University Hospital Zürich, CH-8091 Zürich, Switzerland.
4. Central Biological Laboratory, University Hospital Zürich, CH-8091 Zürich, Switzerland.