Porcine dendritic cells generated in vitro: morphological, phenotypic and functional properties

Despite the central role that dendritic cells (DC) play in immune regulatio n and antigen presentation, little is known about porcine DC. In this study , two sources of DC were employed. Bone marrow haematopoietic cell-derived DC (BM-DC) were generated using granulocyte-macrophage colony-stimulating f actor (GM-CSF) in the presence or absence of tumour necrosis factor-alpha ( TNF-alpha). Monocyte-derived DC (Mo-DC) were generated with GM-CSF and inte rleukin-4 (IL-4). In both systems, non-adherent cells developed with dendri tic morphology, expressing high levels of major histocompatibility complex (MHC) class II. The presence of TNF-alpha increased the BM-DC yield, and en hanced T-cell stimulatory capacity. Both BM-DC and Mo-DC expressed the pan- myeloid marker SWC3, as well as CD1 and CD80/86, but were also CD14(+) and CD16(+). The CD16 molecule was functional, acting as a low-affinity Fc rece ptor. In contrast, the CD14 on DC appeared to differ functionally from mono cyte CD14: attempts to block CD14, in terms of lipopolysaccharide (LPS)-ind uced procoagulant activity (PCA), failed. The use of TNF-alpha or LPS for D C maturation induced up-regulation of MHC class II and/or CD80/86, but also CD14. Allogeneic mixed leucocyte reactions and staphylococcal enterotoxin B antigen presentation assays demonstrated that these DC possessed potent T -cell stimulatory capacity. No T helper cell polarization was noted. Both t he BM-DC and the Mo-DC induced a strong interferon-gamma and IL-4 response. Taken together, porcine DC generated in vitro possess certain characterist ics relating them to DC from other species including humans, but the contin ued presence of CD14 and CD16 on mature and immature porcine DC was a notab le difference.