DNAM-1 also known as CD226 is a glycoprotein expressed on the surface of NK cells, platelets, monocytes and a subset of T cells. It is a member of the Ig-superfamily containing 2 Ig-like domains of the V-set. DNAM-1 is predominantly expressed on T cells and natural killer (NK) cells, playing a vital role in the immune response by facilitating primary adhesion during cytotoxic T lymphocyte-mediated cytotoxicity. This adhesion is essential for the effective targeting and elimination of infected or malignant cells, highlighting DNAM-1′s importance in maintaining immune surveillance and response. DNAM-1′s interaction with ligands on target cells enhances the cytotoxic activity of T cells and NK cells, making DNAM-1 a significant player in the immune system′s ability to combat tumors and infections.