B6-hCD3 Mice

Catalog Number: C001325

Strain Name: C57BL/6NCya-Cd3^tm2(hCD3)/Cya

Genetic Background: C57BL/6NCya

Reproduction: Homozygote x Homozygote

Strain Description

Cluster of differentiation 3 (CD3) is a multimeric protein complex that is essential for T cell activation and antigen recognition. It consists of five different polypeptide chains (γ, δ, ε, ζ, and η) that are noncovalently associated with the T cell receptor (TCR). The TCR is responsible for recognizing antigens presented by antigen-presenting cells (APCs), while CD3 transduces the activation signal into the T cell and activates helper T-cells and cytotoxic T-cells ^[1-2]. The CD3-TCR complex is expressed on the surface of all mature T cells, and its assembly is required for T cell development and function. CD3 plays a crucial role in stabilizing the TCR and facilitating its interaction with antigens. It also recruits signaling molecules to the TCR, which initiates a cascade of events that leads to T cell activation. CD3 is a highly specific T cell marker, and its expression is increased upon T cell activation. This makes it a valuable tool for identifying and characterizing T cells in tissues and blood samples. CD3 staining is also used to diagnose T-cell lymphomas and leukemias. Due to its essential role in T cell activation, CD3 is a promising target for immunosuppressive therapy. Several anti-CD3 monoclonal antibodies have been developed and are being tested in clinical trials for the treatment of autoimmune diseases, such as type 1 diabetes and rheumatoid arthritis ^[3].

This strain is a humanized mouse model of CD3 in which the genes encoding the human CD3 complex were integrated into the mouse Cd3 gene locus through embryonic stem cell (ES) targeting technology to express human CD3 in mice. This model can be used for the mechanism research of T cell activation and antigen recognition, as well as the development, verification, and evaluation of CD3-targeted drugs in immunosuppressive therapy for autoimmune diseases.

Strain Strategy

The mouse Cd3e, Cd3d, and Cd3g genes which encode the three components of the CD3 complex, Cd3ε, Cd3δ, and Cd3γ, were replaced by the corresponding human homologous genes.

Applications

• Elucidation of the molecular mechanisms of T cell activation and antigen recognition.
• Development and evaluation of CD3-targeted immunotherapies for autoimmune diseases.
• Discovery and preclinical validation of novel CD3-targeted drugs.

Validation Data

1. Detection of human and murine CD3 expression in CD45+ cells

Figure 1. Homozygous B6-hCD3 mice express human CD3 (hCD3), while wild-type mice express murine CD3 (mCD3). Human CD3E-positive cells were readily detectable in the peripheral blood (PB) and spleen of homozygous B6-hCD3 mice, with negligible murine CD3E expression. In contrast, wild-type mice expressed only murine CD3E.

2. Assessment of cell subset composition in CD45+CD3+ T cells

Figure 2. T cell subsets are comparable in homozygous B6-hCD3 and wild-type mice. The proportions of CD3+ T cells and their subsets, CD4+ and CD8+ T cells, in the peripheral blood (PB) and spleen of homozygous B6-hCD3 and wild-type mice were indistinguishable.

3. Ex Vivo Tumor Killing Effect of PBMCs

Figure 3. Comparison of the ex vivo killing effect of PBMCs derived from B6-hCD3 mice (B6-hCD3) and human PBMCs (hPBMC). Peripheral blood mononuclear cells (PBMCs) were collected from mice, and both human PBMCs and PBMCs from B6-hCD3 mice were incubated ex vivo with human multiple myeloma cells (MM1R). The killing effect on tumor cells was assessed at different time points. The results showed that the ex vivo killing effect of PBMCs from B6-hCD3 mice on human tumor cells was comparable to that of human PBMCs. In addition, internal testing data showed that, compared with similar models on the market, the PBMCs of this B6-hCD3 mouse model have a better killing effect (data not shown).

Effector cells (E): PBMC; Target cells (T): MM1R; E:T ratio = 1:1 = 2*10^4 : 2*10^4; Time: 24h/48h; Antibody: 1nM BiTE.

Summary

B6-hCD3 mice successfully express human CD3, and homozygous B6-hCD3 mice no longer express mouse CD3, only human CD3. The proportion of T cells and their subgroups, CD4+ T cells and CD8+ T cells, in homozygous B6-hCD3 mice is basically consistent with the wild-type, indicating that the expression of human CD3 does not affect the composition of T cells in mice. In addition, the results of the PBMC killing effect experiment show that the PMBC of B6-hCD3 mice has a similar ex vivo killing effect on human tumors as human PBMCs, indicating that it has similar functions to human PBMC cells.

References

[1]Dong D, Zheng L, Lin J, Zhang B, Zhu Y, Li N, Xie S, Wang Y, Gao N, Huang Z. Structural basis of assembly of the human T cell receptor-CD3 complex. Nature. 2019 Sep;573(7775):546-552.
[2]Dykhuizen M, Ceman J, Mitchen J, Zayas M, MacDougall A, Helgeland J, Rakasz E, Pauza CD. Importance of the CD3 marker for evaluating changes in rhesus macaque CD4/CD8 T-cell ratios. Cytometry. 2000 May 1;40(1):69-75.
[3]Bolt S, Routledge E, Lloyd I, Chatenoud L, Pope H, Gorman SD, Clark M, Waldmann H. The generation of a humanized, non-mitogenic CD3 monoclonal antibody which retains in vitro immunosuppressive properties. Eur J Immunol. 1993 Feb;23(2):403-11.