Fig 1: Apoptotic effects of guanosine-related compounds on PBMCs (a) and cortical T cell ALL xenograft cells (b). All compounds were tested at a concentration of 100 µM. PBMCs (a) were incubated for 72 h with 100 µM of the test compounds in the presence of anti-CD3- and anti-CD28-antibody. ALL xenograft cells (b) were co-cultured with mesenchymal stem cells (MSC cells) for 72 h in the absence of anti-CD3 antibody (open bars) and in the presence of anti-CD3 antibody (filled bars). The nucleoside transport inhibitor NBMPR was used at a concentration of 10 µM. Apoptosis was determined by combined staining with APC-labeled annexin V and propidium iodide. Data are means ± SD from n = 4 (a) or n = 2 (b) independent experiments