| 背景 | This bispecific antibody pairs two of the most extensively characterized rodent clones in immunology: 4-4-20, the classic high-affinity anti-fluorescein antibody, and 145-2C11, the prototypic anti-mouse CD3 epsilon clone used to engage and modulate T cells. It is produced on a mouse IgG2a, kappa framework carrying the LALAPG (L234A/L235A/P329G) Fc mutations, which abolish FcgammaR and C1q engagement so that biological activity derives from the two binding arms rather than from Fc effector recruitment. This design makes it well suited to in vivo and functional studies of redirected T-cell activity in fully immunocompetent mouse models, where the fluorescein arm provides a defined, inert hapten handle for targeting fluorescein-labeled substrates, cells, or scaffolds, and the CD3e arm recruits polyclonal T cells. Supplied at low endotoxin, in bulk milligram-to-gram quantities suitable for repeated dosing cohorts and for research use only (RUO), it supports controlled T-cell engager and hapten-targeting experiments without the confounding effector functions of an intact Fc.
Fluorescein is a small synthetic xanthene hapten (CAS 2321-07-5) with no endogenous counterpart in mammals; because it is biologically inert and absent from the mouse proteome, anti-fluorescein binding provides a clean, orthogonal targeting handle that can be conjugated onto peptides, antibodies, cells, or biomaterials without engaging native tissue. The 4-4-20 clone binds fluorescein with high affinity and quenches its fluorescence on binding. CD3 epsilon (P22646) is an invariant signal-transducing subunit of the CD3 complex that, together with CD3 gamma, delta, and zeta chains, assembles with the T-cell receptor to form the TCR-CD3 complex on all T lymphocytes. CD3e bears an ITAM in its cytoplasmic tail and is essential for surface TCR expression and for propagating antigen-recognition signals into the T cell. Antibody cross-linking of CD3e drives TCR-independent T-cell activation, and CD3-directed antibodies are the canonical means of triggering or redirecting polyclonal T-cell responses. |
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