1. Department of Immunohematology and Blood Transfusion, Tumor Immunology Lab, E3-Q, Leiden University Medical Center, 2300 RC Leiden, Netherlands
2. Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
3. Howard Hughes Medical Research Institute, Cancer Research Laboratory, Department of Molecular and Cellular Biology, University of California at Berkeley, Berkeley, CA 94720