Flow cytometry revealed selleck inhibitor the typical expression of mesenchymal stromal cell markers, MSCs being positive for CD90, CD105, CD73 and negative for CD45, CD34, CD14, among
others. The surface marker profile of MSCs used in our experiments is shown in Table 1. There were no significant differences in surface profiles between B-MSC and S-MSC before co-culture, except for CD146, which showed very low expression levels on S-MSCs and was highly donor-dependent in B-MSCs. Cytometric bead array for several cytokines (n = 10 for day 2 and n = 5 for day 5) revealed high levels of IL-6 in cultures with MSCs, while IL-2, 4, TNF-α and IFN-γ were not detectable both in diluted and undiluted supernatants; IL-10 and IL-17a could be detected only sporadically in some supernatants without differences among the groups (data not shown). Neither IL-1ra, IL-1β nor IL-8 were detectable in the supernatants. CD4+ T cells enriched Ensartinib molecular weight in Tregs showed no significant IL-6 production when compared to co-cultures of S-MSCs and T cells and S-MSC single cultures (P < 0·001 for
comparison with S-MSC single-cell and T cell co-cultures at day 2, P < 0·05 for comparison of S-MSC single-cell cultures and P < 0·001 for comparison of S-MSC/T cell co-cultures at day 5, Fig. 3a,b). IL-6 production in S-MSCs was significantly higher than in B-MSC cultures at day 2 (P < 0·001, Fig. 3a) and significantly higher in S-MSC/T cell
co-cultures than in S-MSCs cultured alone (P = 0·01). At day 5, we observed an important decrease of IL-6 production in all groups, while the IL-6 quantity remained significantly higher in S-MSC/T cell co-cultures when compared to B-MSC/T cell co-cultures (P = 0·006; Fig. 3b). In order to determine whether or not the effects of MSCs on Tregs in co-culture could be reproduced by IL-6, CD4+ lymphocyte cultures enriched in Tregs were supplemented either with 5 ng/ml IL-6, 10 ng/ml IL-6 or supernatants from B-MSC cultures in passage 2. To assess the effective IL-6 concentrations in our supplemented media, IL-6 concentrations were analysed by cytometric bead array at days 2 and 5 of lymphocyte culture. The effective this website concentrations at both time-points were reduced to approximately a third of the initially administered concentrations (Table 2). However, in both the 5 ng/ml and the 10 ng/ml supplemented groups, the natural IL-6 level found in the B-MSC supernatants had been surmounted effectively. Figure 4a,b shows the effects of IL-6 and B-MSC supernatant supplementation on the CD4+ cultures. We could detect a significant decrease of the Treg proportion in non-supplemented T cell cultures compared to both the initial Treg percentage (P < 0·001, Fig. 4a) and T cell cultures supplemented with MSC supernatant (P = 0·003; Fig. 4a). There was no change in the CD4+ percentages between the groups (Fig. 4b).