[Bone marrow-derived dendritic cells rather than spleen-derived dendritic cells can generate regulatory T cells]

There are many evidences that dendritic cells (DC) can establish and maintain immunological tolerance through inducing the differentiation of regulatory T cells Treg. This study was purposed to explore the possibility to gene-rate Treg from bone marrow-derived DC (BM-DC) or spleen-derived DC (spDC) generated CD4(+) CD25(+) FOXP3(+) Treg by induction. Bone marrow immature DC (imDC) induced from bone marrow precursor cells of C57BL/6 mice by GM-CSF and IL-4; after culture for 6 day, imDC were stimulated by LPS for additional 16 hours and the mature DC (mDC) have been got; the spDC were collected from spleen of C57BL/6 mice by MACS. Co-culturing fresh BALB/c mouse CD4(+) T cells with these three sorts of DC above mentioned respectively was performed to generate CD4(+) CD25(+) FOXP3(+) Treg. The expression of FOXP3 in CD4(+) T cells was detected by flow cytometry, and the capacity of different DC generated CD4(+) CD25(+) FOXP3(+) Treg was evaluated. The results showed that stimulated by C57BL/6 immature or mature DC, the positive rate of FOXP3 in BALB/c CD4(+) T cells increased from (8.57 ± 1.14)% to (15.80 ± 1.35)%, (17.93 ± 1.45)% respectively (P < 0.01); while stimulated by spDC, the positive rate of FOXP3 in BALB/c CD4(+) T cells decreased from (8.57 ± 1.14)% to (3.95 ± 0.79)% (P < 0.05). It is concluded that the BM-DC but not spDC can generate Treg from CD4(+) T cells, BM-DC may mediate immune tolerance rather than the immune response.