In vivo at last: Demonstrating the biological credentials and clinical potential of GM-CSF

The pioneering contribution of Professor Donald Metcalf, who passed away in 2014, to the discovery and characterisation of the colony-stimulating factors (CSFs) is exemplified by a seminal contribution to Experimental Haematology by Metcalf and colleagues that detailed the in vivo actions of the newly available recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) in 1987. The results described in this publication promoted GM-CSF actions from fascinating in vitro laboratory phenomena to the recognition that this cytokine was a genuine in vivo regulator of blood cell production and function and provided significant impetus for the clinical development of GM-CSF.