Characterisation of porcine monocyte-derived dendritic cells according to their cytokine profile

The influence of interferon (IFN)-α on the in vitro differentiation of myeloid porcine dendritic cells (DC) was evaluated as the ability of the DC to stimulate to cell proliferation in a mixed leukocyte reaction (MLR), and as their ability to produce cytokines at exposure to bacterial and viral preparations. Porcine monocytes were enriched from purified peripheral blood mononuclear cells (PBMC) by plastic adherence and cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 or in GM-CSF, IL-4 and IFN-α. After 5 days of culture, the cells developed a dendritic morphology and the proportion of cells expressing MHC class II and B7 molecules was increased as determined by flow cytometry. Dendritic cells, differentiated for 5 days in GM-CSF, IL-4 and IFN-α, were able to stimulate both allogeneic and syngeneic PBMC to proliferation in an MLR. The DC produced the Th1 associated cytokines IFN-α at Sendai virus stimulation, and IL-12 at stimulation with plasmid DNA (pre-incubated in the presence of lipofectin), heat-inactivated Actinobacillus pleuropneumoniae, UV-inactivated Aujeszky’s disease virus and live Sendai virus. The heat-inactivated bacteria and Sendai virus also induced production of the Th2 associated cytokines IL-10 and IL-6. The addition of IFN-α during differentiation of DC in GM-CSF and IL-4 enhanced their ability to stimulate allogeneic and syngeneic MLR, but did not alter their ability to produce cytokines.