Clone REA769 recognizes the human CD57 antigen. CD57, also known as HNK-1 or Leu-7, is an antigenic oligosaccharide moiety detected on extracellular proteins of certain cell types. In blood, CD57 is found on 15–20% of mononuclear cells, including subsets of NK and T cells, though not on erythrocytes, monocytes, granulocytes, or platelets. Also, CD57 expression can be found on a variety of neural cell types. CD57 has been shown to be expressed on late stage effector CD8+
T cells. The frequency of CD57+
T lymphocytes is raised in a variety of diseases. CD57 expression is also increased on chronically activated CD8+
T cells in persistent viral infections, such as HIV.