Role of A2a receptor in adenosine-induced heterologous desensitization of RANTES receptors. (A) Effects of adenosine (0.1 mM), NECA (10 μM), CGS21680 (2 μM), ZM241385 (2 μM)/NECA (10 μM), and CPA (0.3 μM) on RANTES-induced chemotaxis of human monocytes. (B) Effects of CGS21680 at 2 μM and 0.2 μM, CGS21680 (0.2 μM)/ZM241385 (0.1 μM) on RANTES-induced chemotaxis of human monocytes. (C) Effects of CGS21680 (2 μM) on RANTES (RAN), MCP-1 (MCP), and fMLF-induced chemotaxis of human monocytes. (D) Effects of CGS21680 (2 μM) on CXCL8/IL-8-induced chemotaxis of human neutrophils. (E) Effects of adenosine (Ade, 0.1 mM), NECA (10 μM), CGS21680 (2 μM), ZM241385 (2 μM)/NECA (10 μM), and CPA (0.3 μM) on RANTES-induced (50 ng/mL) Ca²⁺influx in human monocytes. (F) Effects of CGS21680 (2 μM) on MCP-1- and fMLF-induced Ca²⁺influx (^*P < .001, by 2-way ANOVA analysis; ^**P < .02, Student t analysis).