Differentiation of monocytes into dendritic cells is promoted, along with granulocyte-macrophage colony-stimulating factor, by addition of recombinant IL-4 (1000U/ml, R&D Systems).

Monocytes were transferred into culture bags by sterile welding and cultured for 5 days in serum free medium (CellGro, Cell Genix) in the presence of 100 ng/mL GM-CSF (Leukine, Berlex) and 20 ng/mL IL-4 (Cell Genix).