GM-CSF in the generation of dendritic cells from human blood monocyte precursors: recent advances

Dendritic cells (DCs) play a key role in the orchestration of the immune system by virtue of their capacity to control both immunity and tolerance induction. The functions of DCs depend on the subset as well as their location and activation state. A number of in vitro protocols, developed to recapitulate DC generation from hematopoietic precursors, have suggested the importance of microenvironment and cytokine milieu in driving the generation of DCs endowed with peculiar phenotypic and functional features. Recently, some important concepts on the development of DCs from human blood monocytes have been challenged. The finding that human DCs can be generated from monocytes in the presence of granulocyte/macrophage colony-stimulating factor (GM-CSF) alone points to this cytokine as a direct player, rather than a survival-promoting factor, in the development of DCs with distinct properties. This review summarizes the role of different cytokine cocktails in the in vitro generation of human DCs from blood monocyte precursors, focusing on GM-CSF as a direct player in the generation of functionally distinct DCs.