1. Institute for Immunology and Genetics, German Cancer Research Center, Heidelberg, Federal Republic of Germany.
2. Institute for Radiology and Pathophysiology, German Cancer Research Center, Heidelberg, Federal Republic of Germany.
3. Institute for Pathology of the University of Heidelberg, Federal Republic of Germany.
4. Oncology/Immunology Section, University Children's Hospital, Heidelberg, Federal Republic of Germany.