OBJECTIVETo explore the biological characteristic of third-party-derived tolerogenic DC(tDC) and the influence of third-party-derived tDC on acute graft-versus-host-disease (aGVHD) following allogeneic bone marrow transplantation (allo-BMT) in mice.

METHODStDC from bone marrow cells of D1 mice was cultured with low doses of GM-CSF, IL-10 and TGF-β1D1. The phenotype, expression of cytokines and function associated molecules were identified with FACS and RT-PCR. Mixed lymphocyte reaction was applied to analyze the influence of third-party-derived tDC on allo-CD4(+)T cells proliferation in vitro. Different doses of D1-tDC were adoptive transferred in the aGVHD model in allogeneic BMT which B6 mice as donors and D2 mice as recipients. Survival time, clinical GVHD score and the levels of Th1/2 cytokines in serum were monitored after allo-BMT using the aGVHD model as control.

RESULTStDC expressed lower levels of MHC II and co-stimulatory molecules, such as CD80, CD86 and CD40, even when stimulated by LPS. The results by RT-PCR indicated that tDC expressed low levels of IL-12p40 and high levels of immunosuppressive molecules, such as IL-10, TGF-β, Fas Ligand, indoleamine 2, 3-dioxygenase (IDO) and arginase. In the allogeneic MLR, third-party tDC suppressed allo-CD4(+)T cells proliferation, which was relative to the dose of tDC. In the B6→D2 mouse model, all aGVHD mice died within 18 days. Remarkably, if 10(4) third-party tDC were transferred, 60% mice survived at least 60 days. When the doses of tDC were reduced to 10(3) cells, only 20% of mice survived day 60, and when increased tDC to 10(5), all of the mice died within day 37 after allo-BMT. The cytokine levels in serum indicated that 10(4) tDC-treated mice secreted in vivo high level of IL-10 21d after BMT (P < 0.05), the levels of IL-10 in 10(3), 10(4) and 10(5) tDC-treated mice were (114.23 ± 7.78), (646.18 ± 212.02), (121.97 ± 10.47) ng/L, respectively.

CONCLUSIONThird-party tDC could suppress allo-CD4(+)T cells proliferation in vitro and prevent aGVHD in allogeneic BMT mode, which may be mediated by modulating tolerogenic cytokines secretion, such as IL-10. And this effect was associated with the dose of tDC. Adoptive therapy by transfusing third-party tDC cultured with low doses of GM-CSF, IL-10 and TGF-β1 could significantly prolong the survival of recipients and prevent aGVHD in allogeneic BMT.