Dendritic Cells and B Cells Cooperate in the Generation of CD4+ CD25+ FOXP3+ Allogeneic T Cells

Background. CD4 CD25 Foxp3 regulatory T cells (Treg) play an essential role in immune tolerance, suppressing responses against self-antigens. Additionally, Treg play an important role in maintaining immunosuppression to alloantigens as well as to other antigens. It is well known that in the gut, a subset of dendritic cells produces retinoic acid (RA), which together with transforming growth factor (TGF- ) is able to differentiate naïve T cells into Treg. The aim of this study was to establish the role of antigen-presenting cells (APC) in the differentiation of allogeneic Tregs under the effect of RA and TGF- . Methods. Splenic CD4 CD25 naïve T cells from C57BL/6 mice were co-cultured with splenic CD11c-enriched APC from Balb/c mice in the presence of TGF- , RA, and interleukin (IL-2). After 6 days of culture, cells were analyzed for the expression of Foxp3 by flow cytometry. Additionally, we investigated the role of B cells and dendritic cells (DCs) and their stimulatory capacity in the generation of Tregs. Results. Our results showed that co-culture of naive T cells with the appropriate level of stimulation by APC in the presence of TGF- , RA, and IL-2 provided a new powerful approach to generate allogeneic Treg cells. We demonstrated that although B cells and DCs can generate Tregs by themselves, a mixure of both APC improved their capacity to efficiently generate Tregs. Also, we observed that although the addition of IL-2 to the cultures was not crucial to generate Tregs, it was required to optimize their expansion and cell survival.Supported by FONDECYT grants 1060834, 1060253, 1080416 Universidad Andres Bello grant DI-08-08/I and PFB-16 fron CONICYT, Chile