Dendritic cells differentiated from human monocytes through a combination of IL-4, GM-CSF and IFN-gamma exhibit phenotype and function of blood dendritic cells.

Our previous studies demonstrated that monocytes, when cultured under certain conditions, are able to differentiate into DC-like cells (MoDC) presenting a high accessory activity and low phagocytic function. In the present study, we demonstrate that under the effect of a triple combination of IL-4, IFN-gamma and GM-CSF human blood monocytes are able to differentiate into the cells expressing an identical phenotype and functional features of blood dendritic cells. MoDC stimulated T cell proliferation 20-30 times higher than untreated monocytes, similar to blood DC. They expressed abundant HLA-DR molecules, but only trace amounts of the monocyte/macrophage markers CD16 (FcR III), CD32 (FcR II), and CD14. Phagocytosis of Ig- and complement-opsonized bacteria was reduced by 93%.