Leukocyte immunoglobulin-like receptors (LILRs), also called CD85s, ILTs, or LIRs, are important mediators of immune activation and tolerance that contain tandem immunoglobulin (Ig)-like folds. LILRB1 is encoded within the leukocyte receptor complex on 19q13.4, previously implicated to be a susceptibility region to systemic lupus erythematosus (SLE).LILRB1 binds to a wide range of major histocompatibility complex class I molecules (MHCIs) and transduces negative signals that can, for example, prevent killing of MHCI-expressing cells.LILRB1 transcription is correlated with surface protein expression on NK cells.