DS-MB-00535 is specific for the CD244 cell surface antigen, also known as natural killer receptor 2B4 (NKG2B4). The glycoprotein CD244 is a member of the SLAM family of receptors which is expressed on natural killer (NK) cells, gamma delta T cells, CD14+ monocytes, and a subset of CD8+ T cells. CD244 was originally identified as an activating receptor on NK cells, although recent studies suggest that the receptor may have a wide range of activities including NK cell activation, costimulation, or even inhibition, depending on the cell type and stage of differentiation. The ligand of 2B4 is CD48, a GPI-anchored membrane protein also belonging to the SLAM family.