Anti-Human CD3 [Clone UCHT-1] — Purified in vivo GOLD™ Functional Grade

Clone UCHT-1 is a mouse monoclonal antibody specific for the human CD3? (epsilon) chain, widely used for identifying and activating human T cells in research settings. In in vivo mouse studies, UCHT-1 is typically used in models where human immune cells or tumors are present in mice, known as "humanized" or xenograft mouse models, because UCHT-1 recognizes only human CD3, not murine CD3.

Key applications of UCHT-1 in vivo mouse studies:

• T cell activation: UCHT-1 binds and cross-links the CD3? chain on human T cells, leading to their activation.
• Selective targeting of human T cells: Because its epitope is human-specific, it allows for the study or manipulation of human T cells in mice without affecting mouse T cells.
• Therapeutic studies and cytotoxicity: UCHT-1 can be conjugated to other molecules (such as folate or photosensitive agents) to direct T-cell-mediated cytotoxicity or to trigger targeted effects at tumor sites expressing human T cells or antigens. One example includes UCHT-1-folate conjugates injected into mice bearing human tumor xenografts, with subsequent tumor irradiation to activate the conjugate and modulate tumor growth.
• In vivo imaging and biodistribution: Labeled UCHT-1 may be used for tracking human T cells or for pharmacokinetic studies in mice.

Essential considerations:

• Species specificity: UCHT-1 will not bind to murine CD3 and is used when human T cells are present in the experimental mouse model.
• Functional studies: In vivo, UCHT-1 can induce activation and depletion of human T cells, so careful dosing and timing are required to mimic clinical scenarios or investigate immune responses.
• Conjugate usage: Modified versions (e.g., UCHT-1-folate, UCHT-1-photoactivatable conjugates) are used for site-specific actions, such as inducing cytotoxicity in tumors with localized activation via irradiation.

In summary, clone UCHT-1 is used in in vivo mouse studies primarily in humanized or xenograft models to activate, track, or therapeutically manipulate human T cells, leveraging its human CD3 specificity for targeted immune modulation in mice.

Based on the specifications for clone UCHT-1 anti-CD3 antibodies, the correct storage temperature depends on the storage duration and formulation:

Short-term Storage

The sterile packaged clone UCHT-1 should be stored between 2°C and 8°C for routine storage. The antibody solution must be kept undiluted and protected from prolonged exposure to light. It's crucial to never freeze the antibody during standard storage.

Long-term Storage

For extended storage periods, clone UCHT-1 can be stored at -20°C to -70°C. When using this approach, it's recommended to aseptically aliquot the antibody into working volumes without diluting it first. The antibody can maintain stability for up to 12 months when stored at these frozen temperatures.

Important Storage Considerations

• Avoid repeated freeze-thaw cycles as this may denature the antibody
• Use a manual defrost freezer rather than frost-free freezers
• For Ultra-LEAF™ formulations that contain no preservatives, handle under aseptic conditions
• If slight turbidity occurs during prolonged refrigerated storage, clarify the solution by centrifugation before use

For most routine laboratory applications, storing the sterile packaged clone UCHT-1 at 2-8°C provides adequate stability for up to one month, while frozen storage at -20°C or below is recommended for longer-term preservation.

Commonly used antibodies or proteins paired with UCHT-1 (an anti-human CD3? antibody) in research include other anti-CD3 antibodies (such as OKT3), anti-CD28, markers for T cell subsets, and isotype controls.

Essential context and supporting details:

• OKT3 is another well-known monoclonal antibody that binds a different epitope of the human CD3 complex. Structural studies often compare UCHT-1 directly with OKT3, particularly in mapping their binding sites on CD3?. OKT3 and UCHT-1 are sometimes used in parallel for functional studies or cross-validation of results.
• In cellular assays, UCHT-1 is frequently used alongside:
  • Anti-CD28 antibodies (to provide co-stimulation with CD3-induced activation).
  • T cell subset markers: Common markers include anti-CD4, anti-CD8, anti-CD45RO, and anti-CD62L, allowing for immunophenotyping and assessment of T cell activation, memory, or exhaustion status.
  • Isotype controls: Mouse IgG1 or other immunoglobulin controls to ensure specificity.
• For activation or cytotoxicity assays, UCHT-1 is sometimes used with reagents that mark downstream effects, such as:
  • Annexin V/PI (for apoptosis)
  • CFSE (for cell tracing/proliferation)
  • Calcium indicator dyes (for signaling studies, such as Fluo-3 or Fura Red; flow cytometry data in the literature shows UCHT-1 used to stimulate cells and then measure Ca2+ flux).
• In therapeutic or experimental T cell activation, UCHT-1 Fab fragments may be compared to the full antibody to distinguish effects mediated by monovalent versus bivalent TCR engagement.

Summary table of representative reagents used with UCHT-1:

These combinations are prevalent in immunology research focused on T cell activation, function, or signaling. Where precise combinations are used, details will depend on the experimental aim—e.g., cytotoxicity, activation, or structural comparison.

Clone UCHT-1 is a monoclonal antibody that targets human CD3?, a subunit of the CD3 complex involved in T cell activation. Its scientific importance arises from its broad use in immunology research and therapeutic development. Key findings from its citation in the literature include:

• Mechanism of Action: UCHT-1 binds to a specific region in the ectodomain of human CD3?, blocking or modulating T cell receptor (TCR) signaling. This binding can stabilize the CD3 complex in its active conformation, promoting recruitment of signaling molecules such as Nck to the CD3? proline-rich sequence (PRS), similarly to what occurs in native TCR activation.

• Effects on T Cell Function: Both the full UCHT-1 antibody and its monovalent Fab fragments can enhance activation and cytotoxicity of human ?? T cells against tumor cell lines, including Daudi and Raji lymphoma cells. The effect is not dependent on cross-linking of TCRs, as even monovalent Fab fragments (which cannot cross-link receptors) augment cytotoxic activity and upregulate activation markers (CD69, CD25) and cytokine production (IFN?, TNF?).

• Structural Insights: Structural biology studies revealed that UCHT-1 binds near an acidic region of CD3?, away from the dimer interface, and can stabilize CD3-?/? heterodimers, facilitating structural analysis and understanding of TCR–CD3 assembly.

• Epitope Details: UCHT-1 recognizes CD3? when complexed with CD3? or CD3?, as characterized by immunofluorescence studies. The binding site location is important for both experimental design and therapeutic engineering.

• Experimental Utility: UCHT-1 and its fragments are widely used in flow cytometry, immunoprecipitation, cell stimulation, and as a positive control in T cell functional assays.

• Therapeutic Potential: By enforcing the active CD3 conformation, UCHT-1-modified T cell activation signals can differ qualitatively or quantitatively from those produced by natural ligand engagement alone. This finding supports its role as a tool in dissecting TCR signaling pathways and in developing novel immunotherapies.

In summary, UCHT-1 is a pivotal reagent in T cell research, serving both as a tool to probe basic mechanisms of TCR signaling and as a functional modulator enhancing T cell-mediated cytotoxicity, particularly through stabilization of the CD3 complex in its active conformation.