1B). The positive effect of Rapa on the generation of CD4+CD25+Foxp3+ T cells was only detectable in combination with aCD4. Cultures selleck chemical treated with Rapa alone did not show a significant increase in the Treg frequency compared with that in untreated cultures (Supporting Information Fig. 1). Similarly, in cultures only treated with aCD4+TGF-β or aCD4+RA, no increase in the frequency of Foxp3+ aTreg cells in comparison with an aCD4-only treated culture could be observed. In contrast, effector T cells were strongly reduced under these culture conditions as compared to aCD4 single treatment or untreated cultures. We also tried an alternative protocol

for the generation of Treg cells such as the one described by Wang et al., which is based on the neutralization of interferon gamma (IFN-γ) and IL-4 [20]. Indeed, the neutralization of IFN-γ and IL-4 led to the generation of Foxp3+ Treg cells (Supporting Information Fig. 2). However, the absolute cell number was lower as compared to our protocol aCD4+TGF-β+RA. To further characterise the aTreg cells obtained from

the different culture conditions, we analysed the mRNA expression of Th master switch transcription factors of CD4+CD25+ cells harvested from cultures. Already CD4+CD25+ cells generated under aCD4 monotherapy showed reduced expression of t-bet as compared to CD4+CD25+ cells obtained from an untreated culture, which was not further decreased by adding TGF-β+RA. Interestingly, addition of Rapa counteracted the effect MK-2206 cost of aCD4 treatment. The reverse was true for the expression of RORγt. aCD4+TGF-β+RA aTreg cells displayed increased RORγt expression compared to cells isolated from an untreated culture or isolated from cultures with aCD4 monotherapy (Fig. 1C). To show that we do not promote induction or expansion of effector T cells in our cultures, we have performed CD40L staining of cultured T cells (Fig. 1D). As shown by Schoenbrunn et al. [21], CD40L is only expressed by effector T cells and not by Treg cells. Although

more than 50% of Foxp3− and 14% of Foxp3+ CD25+ cells of untreated cultures do express CD40L, aCD4 monotherapy reduced the CD40L expression for both Foxp3− and Foxp3+ CD25+ cells dramatically. Addition Oxymatrine of TGF-β+RA further reduced the frequency of CD40L+ cells within the Foxp3− population. In contrast, addition of Rapa seemed to boost CD40L expression for both populations. Thus, purified CD25+ T cells from anti-CD4mAb+TGF-β+RA-treated cultures do contain very little contaminating effector T cells. We also studied the cytokine profile of CD4+CD25+ cells obtained from the different cultures. Intracellular detection of Th cytokines could reveal a reduction of IFN-γ as well as IL-17-producing cells within the CD4+CD25+Foxp3− and CD4+CD25+Foxp3+ population for both aCD4+TGF-β+RA- and aCD4+Rapa-treated cultures (Fig. 2A).