Cd19 (CD19 antigen) is expressed in cells of the B lineage in the early stages and throughout B cell development and differentiation, but it is lost on maturation to plasma cells. These targeted knock-in mice express an mCherry/luciferase fusion protein from the mouse Cd19 (CD19 antigen) gene to achieve B cell-restricted fluorescence/bioluminescence in living mice. This dual function protein enables one to link in vivo analysis via bioluminescence imaging with cell-discriminating ex vivo analyses via fluorescence emission. 

When maintained heterozygously, the mutant mouse retains one fully functional copy of the mouse Cd19 gene. Heterozygotes are phenotypically normal and do not display alterations of thymus, spleen, or lymph nodes or develop tumors as shown by gross and histologic examinations. Heterozygous mice are also similar to their wildtype littermates with respect to the number of B cells in peripheral lymphoid tissue. The knock-in allele does not completely knock out expression of the Cd19 gene, but homozygous mutants are likely to show abnormal B lymphocyte development, activation, and differentiation.

Detection of the chimeric CherryLuciferase protein expression via in vivo luciferase imaging (10 minutes after intraperitoneal injection of luciferin into the anesthetized animals) shows that luciferase activity is retained in vivo. Bioluminescence is restricted to the spleen and lymph nodes, consistent with B cell-restricted expression. A linear correlation between tumor weight and bioluminescence light emission has been demonstrated.

Confocal microscopy of spleen sections from heterozygotes confirms the colocalization of CD19 expression with that of mCherry in B cells. Cherry fluorescence has also been identified in peripheral blood mononuclear cell (PBMC) smears of mutant mice. Luciferase activity has been detected in the purified PBMCs.

Crosses of these mice with other models of spontaneous lymphoma (e.g. Tg(Igl-MYC)3Hm mutant mice) enable in vivo longitudinal, spatiotemporal tracking of B cell lymphomagenesis, metastasis, and B cell trafficking, as well as therapeutic responses.

Of Note: The donating laboratory reports that there can be a problem with visualizing cherry fluorescence in this strain. Fixation times longer than 15 minutes are damaging to the mCherry. This has also been observed with GFP. The current opinion is that there is a denaturation of the protein and consequent loss of luminescence or the ability to identify the fluorescent protein. Because cherry is under the control of the CD19 locus, expression is also weak. The donating lab had no problems identifying mCherry fluorescence in their primary construct where the expression in the cells was driven by a strong promoter.

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An mCherry/luciferase fusion protein is expressed from the mouse Cd19 (CD19 antigen) gene to achieve B cell-restricted fluorescence/bioluminescence in living mice. This dual function protein enables one to link in vivo analysis via bioluminescence imaging with cell discriminating ex vivo analyses via fluorescence emission.

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Our minimum guarantee for cryorecovery orders is 2 carriers. To ensure that your colony can be rapidly expanded upon arrival, additional carriers may be added to your order.