Anti-CD3 Antibody [OKT3]

CD3 epsilon

Mouse monoclonal [OKT3] antibody to CD3 epsilon.

Human peripheral blood lymphocytes.

Supplied in Phosphate Buffered Saline with 0.09% Sodium Azide.

This antibody recognises T-cell surface glycoprotein CD3 epsilon chain (CD3e), also known as T-cell surface antigen T3/Leu-4 epsilon. CD3e is a subunit within the multiprotein cell surface receptor TCR-CD3 complex, which is expressed on the surface of mature T cells, NKT cells and thymocytes. The CD3 complex is required for intracellular signaling and for TCR surface expression. Recruitment of the TCR/CD3 complex initiates early events leading to proliferation and differentiation of mature T cells into an effector cell. Mice that lack the CD3e gene exhibit early arrest in T cell development and mutation of the gene in humans has been seen to result in severe combined immunodeficiency (SCID) (DeJarnette et al. 1998, de Saint Basile et al. 2004). Mouse anti Human CD3, clone OKT3 is commonly used in flow cytometry in the phenotyping human T cells. Characterization of the OKT3 clone has shown that it is able to compete and block the binding of the CD3 clones SK7 and UCHT1 to human T cells. The OKT3 clone has also been found to have immunosuppressive properties in vivo. As result of this, the clone was humanized to be used as a therapeutic drug called Muromonomab (Orthoclone). Muromonomab was used as an immunosuppressive including for after solid organ transplants, to prevent the activation of CD4- and CD8- T cells. However, the drug has since been discontinued due to the development of other treatments with similar efficacy and fewer side effects (Reichert 2012).