1 International Center for Infectiology Research, INSERM Unit 1111, Claude Bernard Lyon 1 University, Ecole Normale Supérieure de Lyon, CNRS UMR 5308, 69365 Lyon Cedex 07, France; Transplantation, Nephrology and Clinical Immunology Department, Edouard Herriot Hospital, 69003 Lyon, France olivier.thaunat@chu-lyon.fr.