1 1 Division of Therapeutic Immunology (TIM), Department of Laboratory Medicine (LABMED), Karolinska Institutet, Stockholm, Sweden ; 2 Centre for Allogeneic Stem Cell Transplantation (CAST), Karolinska University Hospital Huddinge, Stockholm, Sweden ; 3 Division of Infection and Immunity, University College London, and National Institute of Health Research Biomedical Research Centre, University College London Hospitals NHS Foundation Trust, London, UK.