Time course of ATP- and BzATP-induced loss of CD23 and L-selectin. B-CLL lymphocytes were incubated with 500 μmol/L ATP (A) or 100 μmol/L BzATP (B) for the indicated times before labeling with anti-CD23 (○) or anti–L-selectin (•). Results are expressed as the mean percentage of initial expression ±SEM (n = 5).