Since the cloning of human interleukin 3 (IL-3) in 1986 [1] and the de
monstration of its proliferative effects on multiple hematopoietic pro
genitor cells, IL-3 has been widely studied to treat different states
of bone marrow failure or hematologic malignancies, to mobilize or exp
and hematopoietic progenitor cells for transplantation, and to support
engraftment after bone marrow transplantation. However, no condition
for the clinical use of IL-3 has been established so far despite its t
heoretical advantages as an early-acting cytokine and in contrast to e
rythropoietin (EPO), G-CSF, or GM-CSF all of which have already been a
pproved for several clinical modalities, Here we shortly review our cu
rrent knowledge about the effects of IL-3 on the molecular and cellula
r level, summarize recent clinical studies with IL-3, and discuss furt
her perspectives for use of this cytokine.