mAbTAFI/TM#16 specifically inhibits thrombin-thrombomodulin activation of purified baboon TAFI (bTAFI). (A) In the absence of the mAbTAFI/TM#16, bTAFI is activated by thrombin (IIa) alone, IIa/thrombomodulin (TM)/unfractionated heparin (UH), plasmin (Pn) alone, and Pn/UH, but most effectively by IIa/TM as determined by activity of bTAFIa (inferred from rate of 3-(2-furyl)acryloyl-Ala-Arg-OH [FAAR] hydrolysis). Addition of the mAbTAFI/TM#16 dramatically reduces bTAFIa activity involving TM-associated activation. (B) The same data displayed as percentage inhibition of TAFI activity, illustrating only activation by IIa/TM (± UH) is blocked by the mAbTAFI/TM#16. Data are expressed as mean (± range); n = 2.