Animal-free Recombinant Human IL-3 expressed in human 293 cells is a glycosylated monomer with an apparent molecular mass of 17 to 40 kDa. This broad molecular mass is attributable to glycosylation, which is absent when this cytokine is expressed in E. coli. A hematopoietic growth factor, IL-3 promotes the survival, differentiation, and proliferation of committed progenitor cells of the megakaryocyte, granulocyte-macrophage, basophil, erythroid, eosinophil, and mast cell lineages. This cytokine can also improve the natural response to disease as part of the body’s immune system.