Center for Human Immunology, Autoimmunity and Inflammation (CHI), National Institutes of Health, Bethesda, USA. jinguo.chen@nih.gov. Center for Human Immunology, Autoimmunity and Inflammation (CHI), National Institutes of Health, Bethesda, USA. Department of Transfusion Medicine, Clinical Center, National Institutes of Health, Bethesda, USA. Fujian Provincial Hospital, Fuzhou, China.