FLT-3L Protein, Human

Fms-like tyrosine kinase 3 ligand (Flt-3 Ligand, or FLT3L) is an alpha-helical cytokine that regulates hematopoiesis by promoting the survival, proliferation, and differentiation of hematopoietic stem and progenitor cells (including dendritic cells, NK cells, and B cells) through binding to the Flt3 receptor (Flt3/Flk-2) and activating the STAT3 signaling pathway. It is expressed as a noncovalently-linked dimer by T cells and bone marrow/thymic fibroblasts and exists in both transmembrane and soluble forms. FLT3L synergizes with other cytokines (e.g., IL-3, GM-CSF, SCF, IL-2, IL-6, IL-7, and IL-15) to enhance hematopoietic cell mobilization, differentiation, and immune cell development.
Recombinant human FLT3L is used in hematopoietic stem cell (HSC) culture expansion (e.g., with SCF and TPO) and dendritic cell (DC) differentiation (e.g., for immunotherapy applications). FLT3L has also been explored as an adjuvant in therapeutic vaccines (e.g., cancer and infectious disease vaccines) to enhance antigen-specific T cell responses or DC mobilization.