The expression of KIR S family members (e.g. KIR2DS1, KIR2DS2 and KIR3DS1), particularly when paired with certain HLA ligands, is associated with increased susceptibility to psoriatic arthritis,49, 50, 51 rheumatoid vasculitis,52 and SLE.53 Here, KIR3DL1 is linked to systemic lupus erythematosus.