Effect of preadministration of α₂M* and α₂M on the plasma clearance of ¹²⁵I-Xa. Various doses (0.5, 1.0, and 2.5 mg) of α₂M*(•) or α₂M (○) were preadministered 1 minute before injection of ¹²⁵I-Xa. Plasma ¹²⁵I-Xa radioactivities were determined at the indicated times, as described in Fig 2.