Muromonab-CD3, also known as OKT3 and Orthoclone OKT3, is a murine monoclonal antibody that specifically targets the CD3 antigen expressed on the surface of human T lymphocytes. It belongs to the immunosuppressive monoclonal antibody class and has historically been used in transplantation medicine.
Muromonab-CD3 binds to the CD3 component of the T-cell receptor complex. This interaction produces rapid modulation and depletion of circulating CD3-positive T cells, thereby suppressing cellular immune responses.
The substance is a mouse-derived IgG2a monoclonal antibody. Unlike conventional chemical APIs, Muromonab-CD3 is a complex biological macromolecule and therefore does not have a conventional small-molecule molecular formula or molecular weight suitable for routine API specification tables.
Muromonab-CD3 was the first monoclonal antibody approved for clinical use in humans. It was historically used for the treatment of acute cellular rejection following solid-organ transplantation, particularly in kidney transplantation.
The FDA Purple Book lists the former Orthoclone OKT3 product as a 1 mg/mL intravenous injection and records its marketing status as discontinued.
Muromonab-CD3 has historically been used as an immunosuppressive monoclonal antibody in transplantation medicine.
Its principal historical application was the treatment of acute cellular rejection following solid-organ transplantation. FDA documentation specifically records its historical use in renal transplant rejection.
Potential pharmaceutical/research applications include:
Website wording recommendation: Because Orthoclone OKT3 is discontinued, use phrases such as “historically used,” “research applications,” and “transplantation immunology” rather than stating that Muromonab-CD3 is currently an approved treatment.
Muromonab-CD3 specifically binds to the CD3 complex on the surface of T lymphocytes.
CD3 is an essential component of the T-cell receptor (TCR) complex, which participates in antigen recognition and T-cell signal transduction.
Binding of Muromonab-CD3 to CD3 initially activates T cells and can produce cytokine release, followed by inhibition and depletion of CD3-positive circulating T cells. This results in suppression of T-cell-mediated immune activity.
| Parameter | Specification |
|---|---|
| Appearance | White crystalline powder or crystals |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 1.0% |