Experimental immunology
Does the contamination of dendritic cells by lymphocytes skew the differentiation of monocytes into macrophages? A pilot study

Immunotherapy based on dendritic cells is currently a very promising therapy for cancer. Methods for the generation of dendritic cells (DCs) in vitro are now being widely investigated. The cellular composition of the culture and functional ability of generated DCs is strongly dependent on precursor cells, culture micro-environment and the type of maturation stimuli. The aim of our study was to investigate the influence of different factors on the differentiation of peripheral blood monocytes into DCs or macrophages. Dendritic cells were generated from adherent monocytes in RPMI medium supplemented with rhGM-CSF, rhIL-4, and autologous serum of lung cancer patients (n=14) and from healthy donors (n=14). The phenotype and morphology of the cultured cells were established in a flow cytometer, as well as by light and confocal microscopy. The level of lymphocyte contamination in the cultures was about 20% in non-small cell lung cancer (NSCLC) patients and 30% in healthy donors. Despite high levels of IL-6 and IL-10 in autologous serum, the monocytes in the NSCLC patients differentiated efficiently in immature DCs CDla+/CD14low or CD1a+/CD14-. The expression of CD14 antigen and percentage of CD14bright cells (macrophages) were significantly higher in cultures from the healthy donors compared to cultures from NSCLC patients. The high number of macrophages was visualized by light and confocal microscopy. The functional status of monocytes and/or cytokines released by lymphocytes during the generation of DCs could modify the differentiation of monocytes into macrophages or DCs.