Effect of pentoxifylline on differentiation and maturation of human monocyte-derived dendritic cells in vitro

Pentoxifylline (PTX) is a drug used for the treatment of vascular disorders, but it also has a positive therapeutic effect in experimental models of some autoimmune diseases. In this work, we studied the effect of PTX on human monocyte-derived dendritic cells (MDDCs). Immature MDDCs were generated in vitro from monocytes in the presence of recombinant human granulocyte macrophage-colony stimulating factor (rhGM-CSF) and recombinant human interleukin-4 (rhIL-4), while mature MDDCs were obtained by cultivation of immature MDDCs with lipopolysaccharide (LPS). PTX (200 μg/ml) was added at the beginning of cell cultivation. We found that PTX significantly impaired differentiation and function of immature MDDCs, as judged by the reduced allostimulatory activity of these cells on allogeneic T cells and down-regulation of costimulatory and adhesion molecules, such as CD86, CD40 and CD54. The maturation of MDDCs in the presence of PTX and LPS was characterized by the decreased expression of maturation marker CD83 and costimulatory molecule CD86, as well as lower stimulation of alloreactive T cells compared to the control MDDCs cultivated with LPS alone. PTX-treated MDDCs which were induced to mature with LPS produced lower levels of TNF-α, IL-12 and IL-18 and higher levels of IL-10 than corresponding control MDDCs. PTX did not significantly alter endocytosis of dextran by both immature and mature MDDCs. Cumulatively, our results show for the first time that PTX might impair differentiation, maturation and function of human MDDCs in vitro, suggesting an additional mechanism of its immunomodulatory activity.