Lymphocyte Activation Gene 3 Simoa

Lymphocyte Activation Gene 3 (LAG-3), also known as CD223, is a type I transmembrane glycoprotein belonging to the immunoglobulin (Ig) superfamily. It is classified as an inhibitory immune checkpoint receptor that plays a crucial regulatory role in the immune system. Structurally related to CD4, LAG-3 is typically expressed on the surface of various immune cells, including activated T cells (both CD4+ and CD8+), T regulatory cells (Tregs), natural killer (NK) cells, and plasmacytoid dendritic cells (pDCs). LAG-3 functions by binding to its primary ligand, MHC Class II molecules, with a higher affinity than CD4, as well as other ligands like Fibrinogen-like protein 1 (FGL1). The engagement of LAG-3 delivers inhibitory signals that negatively regulate the proliferation, activation, cytokine production, and overall effector function of T cells, contributing to T cell exhaustion in conditions like cancer and chronic infection. Due to its role in suppressing the anti-tumor immune response, LAG-3 has emerged as a significant target in the development of next-generation cancer immunotherapies, often in combination with other checkpoint inhibitors like anti-PD-1 antibodies.

Swiss-Prot Accession Number: P18627