CD8 (cluster of differentiation 8) also known as T8 and Leu2, is a surface glycoprotein comprising of α and β chains, which are expressed on immature thymocytes, mature CD8 T cells and some other cell types, e.g., dendritic cells. CD8 exist as either an α/β heterodimer in most thymocytes or α/α homodimer on a subset ofγ/δ TCR-bearing intraepithelial lymphocytes. CD8 is an antigen coreceptor on T cells that associates with the T cell receptor complex during antigen presentation by APC cells through MHC class I. This antibody recognizes the 34 kDa CD8 α chain on the cell surface.