The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia. wentworth@wehi.edu.au. Department of Medical Biology, University of Melbourne, Parkville, VIC, 3010, Australia. wentworth@wehi.edu.au. Department of Diabetes and Endocrinology, Royal Melbourne Hospital, University of Melbourne, Parkville, VIC, Australia. wentworth@wehi.edu.au. The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia. Department of Medical Biology, University of Melbourne, Parkville, VIC, 3010, Australia. School of Public Health, The University of Adelaide, Adelaide, SA, Australia. Clinical Trials Group, Immune Tolerance Network, San Francisco, CA, USA. Eli Lilly and Company, San Diego, CA, USA. University of California at San Francisco, San Francisco, CA, USA. University of South Florida, Tampa, FL, USA. Indiana University School of Medicine, Indianapolis, IN, USA.