Non-Fc receptor-binding humanized anti-CD3 antibodies induce apoptosis of activated human T cells.

Publication Type:

Journal Article

Source:

Journal of immunology (Baltimore, Md. : 1950), Volume 165, Issue 11, p.6205-13 (2000)

Keywords:

Adult, Animals, Antibodies, Monoclonal, Antigens, CD3, APOPTOSIS, Binding Sites, Antibody, CD4-Positive T-Lymphocytes, CD8-Positive T-Lymphocytes, cell cycle, Cells, Cultured, DOWN-REGULATION, Humans, Immunosuppressive Agents, Lymphocyte Activation, MICE, Mitogen-Activated Protein Kinase 1, Muromonab-CD3, PHOSPHORYLATION, Receptors, Antigen, B-Cell, Receptors, Antigen, T-Cell, Receptors, Fc, Solubility, T-Lymphocyte Subsets

Abstract:

Human trials in organ allografts have demonstrated that murine anti-CD3 mAbs are immunosuppressive. By mimicking Ag, anti-CD3 can produce T cell activation, anergy, or death. Activation of resting T cells in vivo results in dose-limiting cytokine release and is caused by Ab-mediated cross-linking of T cells and Fcgamma receptor (FcR)-bearing cells. With the goal of minimizing cytokine-induced toxicity, anti-CD3 have been engineered to lower Fc binding avidity. Preclinical murine studies have indicated that non-FcR-binding anti-CD3 can induce apoptosis of Ag-activated T cells. Since induction of T cell apoptosis may be an important mechanism of immunosuppression by anti-CD3, we tested whether Fc mutations affect the ability of anti-human CD3 to induce apoptosis of activated T cells. We compared wild-type murine anti-CD3, M291, and OKT3 and their humanized, FcR- and non-FcR-binding structural variants in quantitative assays of T cell apoptosis. Non-FcR-binding variants produced more sustainable phosphorylation of extracellular signal-regulated kinase-2, greater release of IFN-gamma, and more effectively caused activation-dependent T cell apoptosis. Non-FcR-binding variants dissociated more quickly from the T cell surface and caused less internalization of the TCR, which then remained available in greater abundance on the cell surface for signaling. Cross-linking of non-FcR-binding variants by antiglobulin enhanced TCR internalization and minimized induction of T cell apoptosis. We conclude that non-FcR-binding, humanized anti-CD3 have improved ability to induce apoptosis of activated T cells, presumably by allowing durable expression of the TCR and sustained signaling.