• CD3 consists of four protein chains (CD3E, CD3D, CD3G and CD3Z), which are important biological markers on the T cell membrane. CD3 can form a TCR/CD3 complex with the T cell receptor, participating in the regulation of T cell antigen recognition, signal transduction and T cell development. CD19 is a biomarker for normal and neoplastic B cells, as well as follicular dendritic cells. CD19 is critically involved in establishing intrinsic B cell signaling thresholds through modulating both B cell receptor-dependent and independent signaling.
• B-hCD3EDG/hCD19/hBCMA mice were obtained by mating B-hCD3EDG mice(110039), B-hCD19 mice(112657) and B-hBCMA mice(110899). In this mice, chimeric human CD3EDG were expressed, while mouse Cd3edg were knocked out. The chimeric CD19 coding sequence containing the extracellular region of human CD19 gene was inserted into mouse Cd19 gene locus site. The exon 1 and part of exon 2 encode the extracellular region of mouse Bcma gene were replaced with human BCMA exon 1 and part of exon 2.
• Human CD3E and CD19 can be detected respectively on T cells and B cells from spleen and blood of homozygous B-hCD3EDG/hCD19/hBCMA mice, but not in wild-type mice. Human BCMA mRNA were detectable only in spleen of B-hCD3EDG/hCD19/hBCMA mice but not in wild-type mice. Humanization of CD3EDG, CD19 and BCMA do not change the overall frequency or distribution of immune cell types in spleen, blood, and lymph nodes. 
• This product is used for the pharmacological and safety evaluation of therapeutic drugs, such as anti-CD19 or anti-BCMA antibodies, bi or tri-specific antibodies, CAR-T cell therapies, and other drugs. Disease areas include oncology and autoimmune diseases.

CD3D: The exons 1-5 of mouse Cd3d gene that encode signal peptide, extracellular domain, transmembrane domain, cytoplasmic region and 3’UTR are replaced by human counterparts in B-hCD3EDG/hCD19/BCMA mice. The promoter and 5’UTR of the mouse gene are replaced by human counterparts. The human CD3D expression is driven by human CD3D promoter, while mouse Cd3d gene transcription and translation will be disrupted. 

CD3G: The exons 1-6 of mouse Cd3g gene that encode signal peptide, extracellular domain, transmembrane domain, cytoplasmic region and 3’UTR are replaced by human counterparts in B-hCD3EDG/hCD19/BCMA mice. The promoter and 5’UTR of the mouse gene are replaced by human counterparts. The human CD3G expression is driven by human CD3G promoter, while mouse Cd3g gene transcription and translation will be disrupted. 

CD19: A chimeric CDS that encodes human CD19 extracellular domain, mouse CD19 transmembrane and cytoplasmic domain, followed by mouse 3’UTR-STOP is inserted right after mouse Cd19 exon 2. The chimeric CD19 protein expression is driven by endogenous mouse Cd19 promoter, while mouse Cd19 gene transcription and translation will be disrupted. 

BCMA: The exon 1 and part of exon 2 encode the extracellular region of mouse Bcma gene are replaced with human BCMA exon 1 and part of exon 2 in B-hCD3EDG/hCD19/BCMA mice.

Strain specific analysis of BCMA mRNA expression in wild-type C57BL/6 mice and homozygous B-hCD3EDG/hCD19/hBCMA mice by RT-PCR. Spleen RNA were isolated from wild-type C57BL/6 mice (+/+) and homozygous B-hCD3EDG/hCD19/hBCMA mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse and human primers. Mouse Bcma mRNA were detectable only in wild-type mice. Human BCMA mRNA were detectable only in B-hCD3EDG/hCD19/hBCMA mice but not in wild-type mice.

Strain specific CD3E expression analysis in wild-type C57BL/6 mice and homozygous humanized B-hCD3EDG/hCD19/hBCMA mice by flow cytometry. Splenocytes (A) and blood cells (B) were collected from wild-type C57BL/6 mice and homozygous B-hCD3EDG/hCD19/hBCMA mice (female, 8-week-old, n=1). Protein expression was analyzed with anti-mouse CD3E antibody (Biolegend, 100312) and anti-human CD3E antibody (BD Horizon™, 562426) by flow cytometry. Mouse CD3E was only detectable in wild-type C57BL/6 mice. Human CD3E was exclusively detectable in homozygous B-hCD3EDG/hCD19/hBCMA mice, but not in wild-type C57BL/6 mice.

Strain specific CD19 expression analysis in wild-type C57BL/6 mice and homozygous humanized B-hCD3EDG/hCD19/hBCMA mice by flow cytometry. Splenocytes (A) and blood cells (B) were collected from wild-type C57BL/6 mice and homozygous B-hCD3EDG/hCD19/hBCMA mice (female, 8-week-old, n=1). Protein expression was analyzed with anti-mouse CD19 antibody (Biolegend, 115507) and anti-human CD19 antibody (Biolegend, 392503) by flow cytometry. Mouse CD19 was only detectable in wild-type C57BL/6 mice. Human CD19 was exclusively detectable in homozygous B-hCD3EDG/hCD19/hBCMA mice, but not in wild-type C57BL/6 mice.

Frequency of leukocyte subpopulations in spleen by flow cytometry. Splenocytes were isolated from wild-type C57BL/6 mice (female, n=3, 8-week-old) and homozygous B-hCD3EDG/hCD19/hBCMA mice (female, n=3, 8-week-old). A. Flow cytometry analysis of the splenocytes was performed to assess the frequency of leukocyte subpopulations. B. Frequency of T cell subpopulations. Percentages of T cells, B cells, NK cells, dendritic cells, monocytes, macrophages, CD4+ T cells, CD8+ T cells and Tregs in B-hCD3EDG/hCD19/hBCMA mice were similar to those in wild-type C57BL/6 mice. Values are expressed as mean ± SEM. 

Frequency of leukocyte subpopulations in blood by flow cytometry. Blood cells were isolated from wild-type C57BL/6 mice (female, n=3, 8-week-old) and homozygous B-hCD3EDG/hCD19/hBCMA mice (female, n=3, 8-week-old). A. Flow cytometry analysis of the blood was performed to assess the frequency of leukocyte subpopulations. B. Frequency of T cell subpopulations. Percentages of T cells, B cells, NK cells, dendritic cells, monocytes, macrophages, CD4+ T cells, CD8+ T cells and Tregs in B-hCD3EDG/hCD19/hBCMA mice were similar to those in wild-type C57BL/6 mice. Values are expressed as mean ± SEM. 

Frequency of leukocyte subpopulations in lymph nodes by flow cytometry. Lymph nodes cells were isolated from wild-type C57BL/6 mice (female, n=3, 8-week-old) and homozygous B-hCD3EDG/hCD19/hBCMA mice (female, n=3, 8-week-old). A. Flow cytometry analysis of the Lymph nodes cells was performed to assess the frequency of leukocyte subpopulations. B. Frequency of T cell subpopulations. Percentages of T cells, B cells, NK cells, CD4+ T cells, CD8+ T cells and Tregs in B-hCD3EDG/hCD19/hBCMA mice were similar to those in wild-type C57BL/6 mice.