Characterization of human monocyte-derived dendritic cells in the presence of leukemic cell soluble products (127.14)

Abstract

Abstract Professional antigen-presenting cells, dendritic cells (DCs) play an important role in controlling tumors, since they are able to initiate an antitumoral immune response. Some works demonstrate that products secreted by solid tumor cells can modulate DCs, however, leukemic cell products are not well studied. Considering that leukemic cells are present in the same place as monocytes (DCs precursor), we analyzed a possible influence of leukemic cell products on DC development and function. For this, monocytes from healthy donors were separated by density gradient and cultured, for 5 days, in the presence of IL-4 and GM-CSF and also with K562 supernatant (SN). In another experiment, immature DCs were cultured with TNF-α for a further 2 days. During a control differentiation, monocytes down regulate CD14, CD16 and CD68 expression and start to express CD1a. In this stage, immature DCs present high endocytic ability. In the presence of SN K562, CD14, CD16 and CD68 expression remained high and CD1a expression was low. However, the addition of SN K562 did not interfere with dextran endocytosis. If activated, DCs increase CD83, CD80 and CD86 expression. It was observed that monocytes differentiated in the presence of SN K562 and then activated expressed less CD83, although CD80 and CD86 expression were not modulated. Finally, these results suggest that products released by leukemic cells affect DC differentiation and these cells become unable to complete their development.