OKT3: Immunology, production, purification, and pharmacokinetics

OKT3 is a monoclonal antilymphocyte antibody produced by a murine hybridoma technique. It differs from polyclonal antilymphocyte antibody preparations in that it is specific for one epitope of the T lymphocyte and is a pure product with batch‐to‐batch standardization. OKT3 binds to the CD3/T‐cell receptor complex, which is located on the surface of mature T lymphocytes and is involved in antigen recognition and cell activation. It appears to produce its potent immunosuppressant effect by: 1) opsonization of circulating T cells; 2) modulation of the CD3/T‐cell receptor complex on T cells; and possibly 3) T‐cell apoptosis. OKT3 also activates T cells and produces the cytokine release syndrome observed with first‐time administration of the drug. OKT3 has a half‐life of approximately 18 h, far shorter than that of human immunoglobulin.