Three rhesus monkeys received a single intravenous injection of 1 mg/kg [¹⁴C]GAS914. Blood was collected at the indicated times. (a) Radioactivity (squares) in whole blood disappeared rapidly from circulation in a biphasic manner. The proportion of radioactivity in plasma versus whole blood was constant (90%), suggesting that GAS914 is not significantly taken up by blood cells (data not shown). Almost no anti-αGal IgM was detected in serum by ELISA after the first bleeding at 5 minutes after injection. There was a slow return of anti-αGal IgM (circles) starting approximately 12 hours after injection. (b) Tissue concentration of total radioactivity 72 hours after administration of 1 mg/kg [¹⁴C]GAS914.