1. Polypeptide Hormone Laboratory, McGill University, Montreal, Quebec, Canada H3A 2A3
2. Laboratory of Cellular Immunology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, U.K.
3. University of Cambridge, Department of Clinical Biochemistry, Addenbrooke′s Hospital, Hills Road, Cambridge CB2 2QR, U.K.