LY9

LY9, also known as CD229 or SLAMF3, is a type I transmembrane glycoprotein belonging to the CD2 family and SLAM subgroup. It functions as a homophilic adhesion receptor on B and T lymphocytes, NKT, and MZ B cells. LY9 interacts with SAP and EAT-2 adapter molecules, modulating innate and adaptive immune responses. It is involved in the development of invariant Natural Killer T (iNKT) cells and acts as an inhibitory receptor for IFN-γ producing CD4+ T cells. Deficiency in LY9 leads to spontaneous autoimmunity, particularly in systemic lupus erythematosus (SLE). Research on LY9 has identified its role in immune regulation and its potential as a therapeutic target for autoimmune diseases and cancer.