Description: The HIT3a monoclonal antibody reacts with human CD3e, a 20 kDa subunit of the TCR complex. Along with the other CD3 subunits γ and δ, the ε chain is required for proper assembly, trafficking and surface expression of the TCR complex. CD3 is expressed by thymocytes in a developmentally regulated manner and by all mature T cells. Crosslinking of TCR with HIT3a initiates an intracellular biochemical pathway resulting in cellular activation and proliferation.