Non-Fc Receptor-Binding Humanized Anti-CD3 Antibodies Induce Apoptosis of Activated Human T Cells

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 Fcγ 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-γ, 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.

Immuno-PET Imaging of Engineered Human T Cells in Tumors

“…It is, to our knowledge, the first approach using a F(ab') 2 -based technology for specific in vivo imaging of human TCR-transgenic T cells by directly targeting the TCR without any impact on the function of targeted T cells. This is of particular interest as direct targeting of the TCR complex has been previously demonstrated to have an impact on T-cell function as well as viability potentially jeopardizing therapeutic efficacy (20,30). As previously reported (22,(31)(32)(33), we also observed alterations of T-cell function and viability by the full IgG anti-TCRmu but not its 2 .…”

B Cells Activated by Lipopolysaccharide, But Not By Anti-Ig and Anti-CD40 Antibody, Induce Anergy in CD8+ T Cells: Role of TGF-β1

“…Furthermore, the expression of FcR on both of the B cells was analyzed for the reason that anti-CD3 Ab-mediated activation of T cells is known to be dependent on the cross-linking of T cells by the FcRs on the accessory cells (31). Therefore, the differential levels of FcRs on B cells could also account for the observed difference in their CD8…”

A humanized non–FcR-binding anti-CD3 antibody, visilizumab, for treatment of steroid-refractory acute graft-versus-host disease

“…Durable expression of the TCR allows sustained signaling by visilizumab leading to apoptosis. 14 We hypothesized that visilizumab might produce selective clonal deletion of activated pathogenic T cells and therefore serve as an ideal agent to treat GVHD. Here we report the initial study of safety, pharmacokinetics, and immunosuppressive activity of antibody visilizumab administered to patients with glucocorticoid-refractory acute GVHD.…”