GM-CSF-based treatments in COVID-19: reconciling opposing therapeutic approaches.

Therapeutics against coronavirus disease 2019 (COVID-19) are urgently needed. Granulocyte-macrophage colony-stimulating factor (GM-CSF), a myelopoietic growth factor and pro-inflammatory cytokine, plays a critical role in alveolar macrophage homeostasis, lung inflammation and immunological disease. Both administration and inhibition of GM-CSF are currently being therapeutically tested in COVID-19 clinical trials. This Perspective discusses the pleiotropic biology of GM-CSF and the scientific merits behind these contrasting approaches.