1. From the Department of Immunology (P.H.T., S.-A.X., S.C.B., M.M., H.F., A.K.M.S.A., A.J.T.G.), Division of Medicine, Imperial College London, Hammersmith Hospital, London, UK.; Jefferiss Research Trust Laboratories (S.C.B., M.O.M.), Wright-Fleming Institute, Division of Medicine, Imperial College London, St Mary’s Hospital, Norfolk Place, London, UK.