Ligands for flt3 receptors capable of transducing self-renewal signals to
regulate the growth, proliferation or differentiation of progenitor cells and stem
cells are disclosed. The invention is directed to flt3-L as an isolated protein,
the DNA encoding the flt3-L, host cells transfected with cDNAs encoding flt3-L,
compositions comprising flt3-L, methods of improving gene transfer to a mammal
using flt3-L, and methods of improving transplantations using flt3-L. Flt3 -L finds
use in treating patients with anemia, AIDS and various cancers.
