About InVivoMAb anti-mouse CD3ε F(ab")₂ fragment

The anti-mouse CD3 F(ab")2 fragment is the antigen binding F(ab")2 fragments of the 145-2C11 monoclonal antibody only. The majority of the Fc fragment has been removed via pepsin digestion. The 145-2C11 antibody F(ab")2 fragment reacts with mouse CD3ε, a 20 kDa transmembrane cell-surface protein that belongs to the immunoglobulin superfamily. CD3ε is one of five polypeptide chains that combine to form the TCR complex. CD3ε is expressed on T lymphocytes, NK-T cells, and to varying degrees on developing thymocytes. CD3 plays roles in TCR signaling, T lymphocyte activation, and antigen recognition. The complete 145-2C11 antibody is commonly used to stimulate T cells in vitro however, when used in vivo activation of resting T cells results in cytokine release and toxicity caused by Ab-mediated cross-linking of T cells and Fcγ receptor-bearing cells. To avoid these complications non-Fc receptor binding F(ab’)2 fragments of the 145-2C11 antibody are commonly used. This non-FcR-binding anti-CD3 induces apoptosis of Ag-activated T cells in vivo by allowing durable expression of the TCR and sustained signaling. Foxp3⁺ Tregs have been shown to be resistant to CD3 antibody-mediated depletion.