Mouse Anti-Human CD223 Antibody (S-R661)

CD223, also known as LAG-3 (lymphocyte-activation gene 3), is a 70 kDa type I transmembrane glycoprotein expressed on activated CD4⁺ and CD8⁺ T cells, regulatory T cells, NK cells and plasmacytoid dendritic cells; it contains four extracellular Ig-like domains that bind MHC class II with roughly 1 000-fold higher affinity than CD4, a connecting peptide cleaved by ADAM10/17 to release soluble LAG-3, and a cytoplasmic tail with an EP repeat and an ITIM-like motif that delivers inhibitory signals by displacing LCK from the CD4/CD8 coreceptor, thereby attenuating TCR signaling, limiting T-cell proliferation, promoting exhaustion in chronic viral infections and tumors, and enhancing the suppressive function of Tregs, making it the third clinically targeted immune checkpoint receptor after CTLA-4 and PD-1.