We used the National Institute of Health Research (NIHR) Cambridge BioResource to recruit 29 healthy volunteers: 19 volunteers homozygous for isoleucine at position 232 in FCGR2B (hereafter referred to as I232 individuals), the common variant associated with normal FcγRIIB function, and 10 volunteers homozygous for the SLE-associated single-nucleotide polymorphism in FCGR2B (hereafter referred to T232 individuals) encoding a receptor that has markedly reduced inhibitory function21,22. Here, FCGR2B is linked to systemic lupus erythematosus.