Flt3l (FMS-like tyrosine kinase 3 ligand) encodes a nonredundant, critical cytokine involved in dendritic cell homeostasis. Its ligand Flt3 is a class III receptor tyrosine kinase expressed on hematopoietic progenitor cells with dendritic cell development potential. FLT3LG in humans (FLT3L in mice) is known to stimulate the growth and proliferation of blood cell progenitors. In this strain, the FLT3LG transgene (founder line 7) expresses human FLT3LG at human physiological levels (~70pg/mL). It is combined with a Flt3 null allele (Flt3em2Mvw), thus reducing competition for the transgenic human cytokine. Mice homozygous for the knock-out allele are viable, fertile and healthy but exhibit reduced cellularity in a number of hematopoietic tissues, reduced numbers of myeloid and lymphoid progenitors in the bone marrow, and reduced numbers of dendritic cells and natural killer cells in the lymphoid organs. The NSG component involves two mutations on the NOD/ShiLtJ genetic background - severe combined immune deficiency (scid) and a complete null allele of the IL2 receptor common gamma chain (Il2rgnull). The scid mutation is in the DNA repair complex protein Prkdc and renders the mice B and T cell deficient. The IL2rgnull mutation prevents cytokine signaling through multiple receptors, leading to a deficiency in functional NK cells. The severe immunodeficiency allows the mice to be humanized by engraftment of human CD34+ hematopoietic stem cells (HSC), peripheral blood mononuclear cells (PBMC), patient derived xenografts (PDX), or adult stem cells and tissues. The immunodeficient NSG mice enable research in human immune function, infectious disease, diabetes, oncology, and stem cell biology. Mice homozygous for all four alleles are viable and fertile - please note that Il2rg is an X-linked gene.This humanized NSG Flt3KO hFLT3LG Tg strain, when engrafted with human HSC, shows improved development of DC, pDC, monocytes, NK cells and mucosal immune system compared to NSG mice.

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This NSG Flt3KO hFLT3LG Tg strain, when engrafted with human HSCs, exhibits improved development of DC, pDC, monocytes, NK cells and mucosal immune system. (<a href="https://www.jax.org/jax-mice-and-services/find-and-order-jax-mice/most-popular-jax-mice-strains/nsg-flt3">See representative engraftment data</a>) This compound mutant strain was developed by combining a transgene expressing human FLT3LG (fms related receptor tyrosine kinase 3 ligand) and a knock-out of its receptor Flt3 (Flt3 interacting zinc finger protein 1) on the immunodeficient NSGTM background (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ, Stock No. <a href="https://www.jax.org/strain/005557">005557</a>). CD34+ humanized NSG-FLT3 (Stock No. 703367) mice can be ordered on our <a href="https://www.jax.org/jax-mice-and-services/preclinical-research-services/humanized-mice/humanized-mice-form">humanized mouse order form</a>.

Sized to accommodate modest cohorts. Multiple orders may be required. <a target="_blank" href="https://www.jax.org/jax-mice-and-services/customer-support" rel="noreferrer">Contact Customer Service</a> for more details.

Homozygous for Flt3<em2Mvw>, Homozygous for Prkdc<scid>, Homozygous for Il2rg<tm1Wjl>, Homozygous for Tg(FLT3LG)7Sz

Homozygous for Flt3<em2Mvw>, Homozygous for Prkdc<scid>, Hemizygous for Il2rg<tm1Wjl>, Homozygous for Tg(FLT3LG)7Sz