huCD28/huCD3 mice are a dual-gene humanized model obtained by mating huCD28 mice (catalog ID: C001817) with huCD3 mice (catalog ID: C001325). This model can be used for the research on autoimmune diseases such as rheumatoid arthritis (RA), Sjögren's syndrome, and systemic sclerosis, transplant rejection, malignant tumors such as T-cell lymphoma, acute myeloid leukemia, and breast cancer, as well as chronic infections such as HIV. It is also used for the screening, development, and safety evaluation of CD28/CD3-targeted drugs.

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]. The CD19 gene encodes a member of the immunoglobulin gene superfamily. As a key co-receptor in the B cell receptor (BCR) signaling pathway, it is crucial for B cell development, activation, and differentiation. CD19, a pan-B-cell marker exclusively expressed in the B cell lineage, remains stable throughout B cell development, from pro-B cells to mature and memory B cells. It acts as a positive regulator of BCR signal transduction by forming a B cell-specific signaling complex with CD21 (complement receptor 2), CD81 (tetraspanin), and CD225 (Leu13), which lowers the threshold for antigen-induced B cell activation ^[4]. Dysregulation of CD19 is strongly linked to autoimmune diseases such as systemic lupus erythematosus (SLE) and B cell malignancies like acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma. Mutations in this gene are associated with common variable immunodeficiency 3 (CVID3), characterized by impaired B cell differentiation and hypogammaglobulinemia. Owing to its B-cell-specific expression, CD19 has become a pivotal target for immunotherapy. For example, anti-CD19 CAR-T cell therapy (e.g., Tisagenlecleucel) has shown remarkable efficacy in refractory or relapsed ALL ^[5]. Recent studies have also explored CD19-targeted bispecific antibodies (e.g., blinatumomab) to enhance tumor cell clearance ^[6]. huCD19/huCD3 mouse is a dual-gene humanized model generated by crossing huCD3 mice (Catalog No.: C001325) with huCD19 mice (Catalog No.: C001731). This strain is applicable for the development, validation, and preclinical evaluation of bispecific antibodies targeting human CD3/CD19, as well as for research on malignant tumors such as B-cell lymphoma and immunosuppressive therapies for autoimmune diseases. It serves as an ideal platform for the development of combination therapies.

Cluster of Differentiation 3 (CD3) is a protein complex that acts as a co-receptor for T cells and is involved in the activation of cytotoxic T cells (CTLs) and helper T cells (THs). CD3 consists of five polypeptide chains: γ, δ, ε, ζ, and η, all of which are transmembrane proteins. The transmembrane regions of CD3 molecules connect with the transmembrane regions of TCR's two polypeptide chains through salt bridges, forming the TCR-CD3 complex, which is essential for T cell antigen recognition ^[1-2]. After TCR recognizes an antigen, the activation signal is transduced by CD3 into the T cell. CD3 is highly specific at all developmental stages of T cells, thus it is considered a T cell-specific immunohistochemical marker. Additionally, CD3 is present in almost all T cell lymphomas and leukemias and can be used to distinguish between morphologically similar B cell and bone marrow tumors. Due to its significant role in T cell activation and antigen recognition, CD3 is an important drug target in immunosuppressive therapy for type 1 diabetes and other autoimmune diseases ^[3]. Cluster of Differentiation 20 (CD20), also known as MS4A1, is a functional receptor molecule on the surface of B lymphocytes, closely associated with B cell activation, signal transduction, and growth regulation. CD20 is expressed in the late stages of B cell lymphopoiesis and disappears after differentiation into plasma cells. Therefore, CD20 is expressed from pre-B cells to mature B cells, but not in plasma cells ^[4]. It is highly expressed in most B-cell lymphomas. Since 1997, the advent of anti-CD20 monoclonal antibodies such as Rituximab has significantly improved the treatment outcomes for B cell malignancies. Therapeutic monoclonal antibodies (mAbs) targeting the CD20 antigen are widely used in research on B cell-depleting tumor therapies to treat various cancers and autoimmune diseases ^[5-7]. With the development of combination therapies, CD3/CD20 bispecific antibodies have gained significant attention from researchers. These antibodies can bind to CD20 on cancer cells and CD3 on T cells, promoting local T cell activation and cancer cell killing ^[8]. Currently, four CD3/CD20 bispecific antibodies have been approved for marketing: Epcoritamab (AbbVie/Genmab), Mosunetuzumab (Roche/Biogen), Glofitamab (Roche), and Odronextamab (Regeneron). The huCD3/huCD20 mouse is obtained by crossbreeding huCD3 mice (Catalog No.: C001325) with huCD20 mice. It can be used for the development of CD3/CD20-targeted drugs, as well as for research in tumor immunotherapy and autoimmune disease-related drugs.

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]. The DLL3 (Delta-like canonical Notch ligand 3) gene encodes a transmembrane protein belonging to the Delta/Serrate/Lag-2 (DSL) family of ligands. Functioning within the highly conserved Notch signaling pathway, DLL3 exhibits a unique, inhibitory role, contrasting with the canonical activating function of other Notch ligands. It is believed to antagonize Notch signaling by preventing ligand-receptor interactions or by promoting receptor degradation, a mechanism critical for establishing proper cell fate decisions during development ^[4]. This is particularly evident in the formation of somites, where DLL3's function is essential for the rhythmic segmentation of the presomitic mesoderm ^[5]. While its expression is largely restricted to fetal tissues and progenitor cells in healthy adults, DLL3 is ectopically and highly expressed in a number of neuroendocrine tumors, including small cell lung cancer (SCLC), making it a promising therapeutic target. Pathogenic variants in the DLL3 gene are directly linked to Spondylocostal dysostosis type 1, a congenital disorder of vertebral segmentation ^[6]. The B6-huCD3/huDLL3 mouse is a dual-gene humanized model obtained by mating B6-huCD3 mice (catalog number: C001325) with B6-huDLL3 mice (catalog number: C001854). This model can be used for studying the pathological mechanisms and treatment methods of tumors and autoimmune diseases, as well as for the development of CD3/DLL3-targeted drugs.

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]. The TNFRSF17 gene, also known as BCMA, encodes a protein belonging to the tumor necrosis factor receptor superfamily. This protein is predominantly expressed in mature B lymphocytes, particularly plasma cells, with lower expression in early B cells and non-B cells ^[4-5]. As a type III transmembrane glycoprotein, TNFRSF17 plays a critical role in B cell survival and differentiation, acting as a key regulator of B cell maturation ^[5]. Functionally, TNFRSF17 primarily acts as a receptor for the B cell-activating factor (BAFF). Upon BAFF binding, it activates both the classical NF-κB pathway and the non-classical MAPK8/JNK pathway, subsequently regulating downstream gene expression to promote B cell survival, proliferation, and antibody secretion. Furthermore, TNFRSF17 can interact with TNFR-associated factors (TRAFs) 1, 2, and 3, further mediating physiological processes related to cell differentiation and growth ^[4-5]. Multiple studies have demonstrated that the TNFRSF17 gene and its protein are associated with various B cell-related diseases. Notably, this gene exhibits abnormally high expression in diseases such as multiple myeloma and systemic lupus erythematosus, rendering it a potential therapeutic target for these conditions ^[6-7]. The B6-hCD3/hBCMA mouse is a dual-gene humanized model generated by crossing B6-hCD3 mice (Catalog No.: C001325) with B6-hBCMA (TNFRSF17) mice (Catalog No.: C001630). This model can be used for researching the pathological mechanisms and therapeutic approaches of diseases such as autoimmune diseases and multiple myeloma, as well as for the development of CD3/BCMA-targeted drugs.

Cluster of Differentiation 3 (CD3) is a protein complex that acts as a co-receptor for T cells and is involved in the activation of cytotoxic T cells (CTLs) and helper T cells (THs). CD3 consists of five polypeptide chains: γ, δ, ε, ζ, and η, all of which are transmembrane proteins. The transmembrane regions of CD3 molecules connect with the transmembrane regions of TCR's two polypeptide chains through salt bridges, forming the TCR-CD3 complex, which is essential for T cell antigen recognition ^[1-2]. After TCR recognizes an antigen, the activation signal is transduced by CD3 into the T cell. CD3 is highly specific at all developmental stages of T cells, thus it is considered a T cell-specific immunohistochemical marker. Additionally, CD3 is present in almost all T cell lymphomas and leukemias and can be used to distinguish between morphologically similar B cell and bone marrow tumors. Due to its significant role in T cell activation and antigen recognition, CD3 is an important drug target in immunosuppressive therapy for type 1 diabetes and other autoimmune diseases ^[3]. The EPCAM gene encodes a transmembrane glycoprotein, Epithelial Cell Adhesion Molecule (EPCAM), also known as CD326 or Trop-1, which mediates calcium-independent homotypic cell adhesion and participates in fundamental processes including cell adhesion, migration, proliferation, and signal transduction, thereby maintaining epithelial tissue integrity ^[4]. While normally expressed on the surface of epithelial cells in organs such as the gastrointestinal tract, lungs, and skin, EPCAM is frequently overexpressed in various cancers, including colorectal, breast, and pancreatic carcinomas, but is largely absent or weakly expressed in healthy squamous epithelia ^[4]. Structurally, EPCAM comprises an extracellular domain (EpEX) mediating intercellular adhesion, a transmembrane domain, and a short intracellular domain (EpICD). Upon proteolytic cleavage by ADAM17 and γ-secretase, EpICD translocates to the nucleus, activating oncogenic pathways such as Wnt/β-catenin, ERK, and FAK-AKT, which promotes epithelial-mesenchymal transition (EMT), tumor progression, and metastasis ^[5]. Notably, EPCAM serves as a marker for circulating tumor cells (CTCs) and cancer stem cells, and its downregulation during EMT can complicate advanced cancer detection ^[5-6]. Furthermore, dysregulated EPCAM expression is associated with congenital tufting enteropathy (CTE), a severe intestinal epithelial dysfunction ^[5]. Given its involvement in tumor metastasis through interaction with HGFR (c-Met), targeting EPCAM with strategies like the neutralizing antibody EpAb2-6 in combination with HGFR inhibitors has shown promising preclinical efficacy ^[7]. The B6-hCD3/hEPCAM mouse is obtained by crossbreeding B6-hCD3 mice (Catalog No.: C001325) with B6-hEPCAM mice. It can be used for the development of CD3/EPCAM-targeted drugs, as well as for research in tumor immunotherapy and autoimmune disease-related drugs.