1. Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48105
2. Department of Immunology, Schering-Plough Research Institute, Kenilworth, New Jersey 07033
3. Human Genome Research, Palo Alto, California 94304
4. Department of Experimental Medicine and Pathology, University of Rome, 00167 Rome, Italy
5. DNAX Research Institute for Cellular and Molecular Biology, Palo Alto, California 94304
6. Instituto Dermopatico dell'Immacolata-IRCCS, 00167 Rome, Italy