The HIT8a monoclonal antibody reacts with the human CD8a molecule, an
approximately 32-34 kDa cell surface receptor expressed either as a heterodimer
with the CD8 beta chain (CD8 alpha/beta) or as a homodimer (CD8 alpha/alpha).
A majority of thymocytes and a subpopulation of mature T cells and NK cells express CD8a.
CD8 binds to MHC class I and through its association with protein tyrosine kinase p56lck
plays a role in T cell development and activation of mature T cells.