Fig. 6
Adenosine contained in CeCa-MSC supernatants strongly increases the cAMP levels in CD8+ T cells. CD8+ T-cells (4 × 105) previously stimulated with beads containing anti-CD2/CD3/CD28 antibodies in a 2:1 ratio, were cultured during 30 min in the presence of supernatants (Sup) obtained from NCx-MSC or CeCa-MSC cultures. In other cases, cells cultured in the presence of synthetic Ado (500 μM), caffeine (300 μM), Ado:caffeine (500 μM:300 μM), Ado: ZM241385 (500 mM:1 mM), Ado: ZM241385:caffeine (500 μM:1 μM:300 μM), or the ARs agonist, 5′-N-ethylcarboxamidoadenosine (NECA; Sigma-Aldrich) (5 μM) were seeded independently to establish appropriate controls. cAMP levels of the CD8+ T cells were determined as indicated in “Methods” section. Significant differences *(P < 0.05) and **(P < 0.01) were obtained compared with CD8+ T-cells cultured with beads in the absence of Ado (negative control of inhibition). Data are representative of three independent experiments, and the mean ± SEM are shown