Demonstration of extracellular adenosine or CGS21680-induced thymocyte death by PI versus Annexin V staining of cells.

Ex vivo thymocytes were incubated 16 to 20 hours at 37°C in 5% CO₂ incubator in the presence of adenosine or adenosine analog CGS21680, and the extent of apoptosis or cell death was measured by flow cytometry as described in “Materials and methods.” (A) Loss of live cells in the presence of adenosine or CGS21680. (B) Effects of different concentrations of adenosine and CGS21680 on thymocytes. CGS21680-induced apoptosis of thymocytes reached plateau at as low as 0.3 μmol/L.