Ms Recom Flt3/Flk-2 Ligand, 10 µg

A hematopoietic cytokine from STEMCELL Technologies, Flt3/Flk-2 (Fms-like tyrosine kinase 3/fetal liver kinase-2) ligand regulates the proliferation, differentiation, and survival of hematopoietic stem and progenitor cells and contributes to development of the immune system. The cytokine exists as membrane-bound and soluble isoforms, both biologically active, and signals through the class III tyrosine kinase receptor Flt3/Flk-2 (CD135). It is produced by uncommitted and committed hematopoietic cells and stromal fibroblasts, while receptor expression is restricted to hematopoietic stem and progenitor cells and is also detected in the brain, placenta, and testis.

Together with stem cell factor and thrombopoietin, the ligand is commonly used to promote expansion of primitive hematopoietic cells in culture. In combination with myeloid cytokines such as GM-CSF, G-CSF, or M-CSF, it enhances growth and numbers of clonogenic myeloid progenitor cells, while acting in synergy with IL-3, IL-4, IL-7, IL-11, IL-12, IL-15, GM-CSF, and TNF-α to regulate development of lymphoid progenitor cells including dendritic cell, B cell, T cell, and NK cell progenitors. The ligand has no significant effect on erythropoiesis or megakaryopoiesis, and is used as a serum-free culture supplement for expansion of human hematopoietic cells, including CD34+ populations.

The mouse recombinant protein is expressed in E. coli with a predicted molecular mass of 18.6 kDa and purified to ≥ 95%. It is lyophilized from a sterile-filtered solution containing sodium phosphate at pH 7.5. Endotoxin level is ≤ 1 EU/μg protein as measured by kinetic Limulus amebocyte lysate (LAL) analysis. Specific activity is ≥ 1 x 10^5 units/mg, with an EC50 ≤ 10 ng/mL in a cell proliferation assay using AML5 cells; a representative assay gave an EC50 of 1.3 - 2.0 ng/mL. The product is cross-reactive with human and rat. Store at -20°C to -80°C; stable as supplied for 12 months from date of receipt. Reconstitute in sterile water to at least 0.1 mg/mL by pipetting the solution down the sides of the vial; do not vortex.