[Influence of 1,25(OH)(2) vitamin D(3) on maturation of human dendritic cells and DC-mediated immune tolerance].

This study was aimed to investigate the effect of 1,25(OH)(2) vitamin D(3) [1,25(OH)(2) Vit D(3)] on the differentiation, maturation and function of human dendritic cells (DC) in vitro and its mechanism. Human peripheral blood mononuclear cells were induced to differentiate to DC in vitro. The DC in test group were cultured with 1,25(OH)(2) Vit D(3) 1 nmol/L for 9 d, while the DC in control group were cultured with the equivalent of absolute alcohol. The expression of co-stimulatory molecules on DC were analyzed by flow cytometry. T cell proliferation induced by DC was assessed by MTT method. The expression of indoleamine 2, 3-dioxygenase (IDO) protein was determined by Western blot. The results showed that compared with the control group, the expression of CD80, CD83 and CD86 on DC in test group was significantly down-regulated (P < 0.05), while the CD1a was up-regulated (P < 0.05). The expression rate of CD80, CD83, CD86, CD1a in test group were (40.43 ± 9.83)%, (20.04 ± 4.73)%, (14.45 ± 5.38)%, (58.48 ± 10.72)% respectively, while in control group were (29.36 ± 13.34)%, (35.91 ± 10.19)%, (27.15 ± 11.64)%, (72.20 ± 12.79)% respectively. Compared with the control group, 1,25(OH)(2) Vit D(3)-treated DC exhibited a markedly reduced ability to stimulate allogenic T cell proliferation and up-regulated IDO protein expression.It is concluded that 1,25(OH)(2) Vit D(3) efficiently inhibits the maturation of DC and DC-mediated T cell proliferation, which may be related to the up-regulation of IDO protein expression.