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

Clone UCHT-1 is a monoclonal antibody specific for human CD3?, frequently used in in vivo mouse studies involving human immune cells engrafted into mice (i.e., humanized mouse models).

• UCHT-1 does not recognize mouse CD3; its use is generally restricted to models where human CD3-positive cells are present (such as immunodeficient mice reconstituted with human PBMCs, hematopoietic stem cells, or tumors expressing human CD3).

• Mechanisms of use in mouse studies:

  • Activation or depletion of human T cells: UCHT-1 binding/crosslinking leads to activation and/or depletion of human T cells via the CD3/TCR complex.
  • Targeted delivery or functional assays: UCHT-1 has been conjugated to molecules (e.g., folate, drugs, photosensitive groups) to locally modulate human T cells within the mouse, such as photolysis-driven tumor targeting.
  • Immunophenotyping: UCHT-1 is used to identify, isolate, or quantify human T cells in mouse tissues via flow cytometry or immunohistochemistry.

Example (from the literature):

• A published study administered UCHT-1–folate conjugates into mice bearing tumors composed of human cells, then used local UV irradiation to activate the antibody conjugate in situ, thus targeting human T cells in a spatially controlled manner.

Key points for in vivo use:

• Application is restricted to humanized or xenograft models with human T cells.
• Formats exist that are pre-validated for in vivo mouse injection (low endotoxin, bulk purified).
• Common endpoints include measurement of human T cell activation, depletion, or anti-tumor immune effects—always specific to human (not endogenous mouse) CD3.

Summary Table: UCHT-1 Use in Mouse Studies

Note: Since UCHT-1 is mouse IgG1 and does not cross-react with mouse CD3, it is not used for immunomodulation in normal, non-humanized mice.

The correct storage temperature for sterile packaged clone UCHT-1 (anti-human CD3 monoclonal antibody) is between 2?°C and 8?°C, undiluted and protected from prolonged exposure to light.

Additional pertinent details:

• Do not freeze standard liquid antibody formulations, as freezing may denature the antibody or cause loss of activity.
• Some suppliers indicate that short-term storage (up to one month) at 2–8?°C is acceptable, but for longer-term storage—particularly for functional or azide-free/low preservative formulations—aseptically aliquoting and freezing at ? -20?°C or ? -70?°C is recommended to maintain stability.
• Always consult the lot-specific datasheet or instructions from the specific supplier, as formulation and stabilizers can vary, potentially affecting storage requirements.

In summary:

• Routine storage: 2–8?°C, undiluted, avoid light, do not freeze.
• Long-term storage (if required and formulation allows): ? -20?°C or ? -70?°C, aliquoted, avoid repeated freeze-thaw cycles.

If your product is a standard liquid, azide-containing or preservative-containing UCHT-1 antibody: use 2–8 °C.If your product is purified, preservative-free, or for in vivo/functional use: long-term storage at ? -20?°C or ? -70?°C is preferable after aliquoting.

UCHT-1 is commonly used in conjunction with other antibodies or proteins targeting distinct immune cell markers to identify or characterize cell populations in immunological studies, especially by flow cytometry and immunohistochemistry.

Typical antibodies and proteins used alongside UCHT-1 include:

• CD19: An antibody frequently combined with UCHT-1 to distinguish T cells (CD3+) from B cells (CD19+) in mixed lymphocyte populations.
• OKT3: Another monoclonal antibody directed against CD3?, often compared or used with UCHT-1 in functional or binding studies of the T cell receptor complex.
• Secondary reagents: Such as APC-labeled anti-mouse IgG antibodies, commonly employed for detection when UCHT-1 is used as an unconjugated primary antibody.
• Other T or B cell markers: In multi-color panels, antibodies against markers like CD4, CD8 (T cell subsets), CD45, or CD20 (other B cell markers) are typically included alongside UCHT-1 to further delineate or characterize lymphocyte subsets.

In experimental protocols, UCHT-1 has also been referenced in combination with:

• Fab fragments (produced from UCHT-1 itself), especially in studies aiming to distinguish activating versus non-activating effects on T cells.
• Chemical agents or activating proteins: Such as concanavalin A for cell stimulation or zoledronate for ?? T cell expansion in cytotoxicity assays.

These combinations allow for precise immunophenotyping and functional interrogation of immune cells in both basic and translational research contexts.

Key findings from clone UCHT-1 citations center on its ability to bind and stabilize the CD3? subunit of the T cell receptor (TCR) complex, enhancing T cell activation and cytotoxicity, particularly in human ?? T cells.

• UCHT-1 binding stabilizes the active conformation of CD3: UCHT-1 binds the CD3? subunit at a region opposite the interface with CD3?, occluding this region from direct TCR interaction and stabilizing the CD3?/? heterodimer. Structural studies revealed high-affinity interactions involving multiple hydrogen bonds and salt bridges between UCHT-1 and CD3?.
• Enhancement of ?? T cell activation and tumor killing: Both full UCHT-1 antibody and its monovalent Fab fragments are shown to enhance tumor cell killing by human V?9V?2 ?? T cells. Notably, this enhancement occurs without requiring TCR cross-linking, implicating stabilization of the CD3 active conformation as the key mechanistic event.
• Mechanistic insight—Nck recruitment: UCHT-1-induced stabilization of the active CD3 conformation promotes recruitment of the signaling adaptor Nck to the proline-rich sequence (PRS) of CD3?, a mechanism previously established for ?? TCRs and now shown for ?? TCRs as well. This recruitment can be blocked by specific inhibitors, indicating pathway specificity.
• Functional outcomes of UCHT-1 treatment: The presence of UCHT-1 Fab fragments boosts ?? T cell activation markers (CD69, CD25) and proinflammatory cytokine expression (IFN?, TNF?). These effects are above and beyond those achieved by stimulation with natural phosphoantigen ligands alone.
• Structural biology applications: UCHT-1’s strong affinity for CD3 has enabled the successful crystallization of CD3?/? heterodimers for structural analysis, facilitating fundamental understanding of TCR architecture.

In summary, UCHT-1 serves as a powerful tool for both structural and functional interrogation of T cell activation via CD3?, with direct translational implications for modulation of immune responses and tumor cell killing by ?? T cells.