Swine monocytes constitute a heterogeneous cell population containing subsets with distinct functional capacities or representing different maturational stages. Based on the expression of CD163, we have recently identified two monocyte subpopulations. In this study, we investigate the ability of both CD163- and CD163+ monocytes to differentiate into dendritic cells (DCs) in the presence of GM-CSF and IL-4. Monocyte differentiation into DC is accompanied by an up-regulation of the expression of swine leukocyte antigen (SLA) I, SLA II and CD80/86 molecules, and a decrease in the expression of CD14, CD16 and CD163. These DC express the pan-myeloid marker SWC3 and display typical dendritic cytoplasmic projections. When monocytes are split into CD163+ and CD163- cells, both subsets give rise to DC. However, compared to CD163- monocyte-derived DC (MoDC), CD163+ MoDC appear to have reached a more advanced stage of maturation, expressing higher levels of SLA II and CD80/86 and inducing more efficiently proliferation of T cells to recall antigens and alloantigens.