YTS169-RAT-IgG2b

CD8 is a glycoprotein present on approximately one-third of T cells in lieu of CD4. Similar to CD4, it binds to a monomorphic region MHC, although it binds to class I rather than to class II antigens. CD8 defines cytotoxic effector cells and perhaps subsets of natural killer and regulatory cells. It facilitates binding between the TCR and class I molecules and is important in protective immune lysis of virally infected parenchymal cells. CD8+ T cells are known to infiltrate allografts and to participate in allograft rejection. Despite this demonstrated role in rejection, CD8 has not been successfully targeted in transplantation, perhaps because CD8+ T cells are recruited late in an alloimmune response and have less regulatory control over immune responses than CD4+ T cells.