Immature dendritic cells phagocytosing human spleen cells treated by PUVA present the characteristics of regulatory dendritic cells

: Objective To investigate the effect of psoralen combined with A-band ultraviolet (PUVA)-treated human spleen lymphocytes on the phenotype and function of immature dendritic cells (imDCs). Methods Human peripheral blood mononuclear cells (PBMCs) were isolated and induced to produce DCs by interleukin-4 (IL-4) and recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF). On the sixth day, the imDCs were obtained and stimulated by lipopolysaccharide (LPS). One day later, mature DCs were harvested. Human spleen cells (SPs) were isolated and treated with PUVA to prepare apoptotic PUVA-SPs. Co-culture of imDCs with PUVA-SPs resulted in extracorporeal photochemotheraputic DCs (ecpDCs). Co-culture of imDCs with SPs resulted in SP-DCs. The expressions of CD11c, CD83 and CD86 were detected by flow cytometry. The levels of IL-10 and IL-12 in the supernatants of the above cells were determined by ELISA. Results The early apoptosis rate of PUVA-SPs was (94.21±3.75)%. There was no significant difference in the expressions of CD83 and CD86 between imDCs and ecpDCs. But the positive rates of CD83 and CD86 in ecpDCs were lower than those in DCs. However, the positive rates of CD83 and CD86 in SP-DCs were significantly higher than those of the imDCs. Conclusion The imDCs phagocytosing apoptotic human SPs present phenotype and function of regulatory DCs.