Human IL-3 Animal Free Recombinant Protein, eBioscience?. Interleukin 3 (IL-3), also called Mast Cell Growth Factor (MCGF), Multi-Colony Stimulating Factor (multi-CSF), or Eosinophil-CSF (E-CSF), is produced by activated T cells, mast cells and eosinophils. IL-3 is a hematopoietic growth factor that stimulates colony formation of erythroid, megakaryocyte, neutrophil, eosinophil, basophil, mast cell and monocytic lineages. Most of these functions are enhanced or dependent on co-stimulation with other cytokines. Human and mouse IL-3 share only 29% sequence identity at the amino acid level. The bioactivity of IL-3 is highly species specific. For example, human IL-3 has no activity on mouse cells. IL-3 is a potent growth promoting cytokin