The 3E8 anti-HK antibody delays aPTT but not PT and prevents Aβ42-induced intrinsic coagulation in human plasma. (A) The 3E8 HK antibody delayed aPTT. Citrated human plasma was incubated with buffer, 3E8 (0.05 μM, 0.15 μM, 0.75 μM, 3.75 μM), or control IgG (3.75 μM) at 37°C for 20 minutes. Intrinsic coagulation was initiated by adding aPTT reagent and CaCl₂ solution. Absorbance readings were recorded every 5 seconds at 350 nm, and aPTT was determined. 3E8 did not significantly affect aPTT at 0.05 μM, but it significantly delayed the aPTT at 0.15 μM. However, higher amounts of 3E8 did not cause further delay. Control IgG did not affect aPTT. (B) The 3E8 HK antibody did not affect PT. Citrated human plasma was incubated with buffer, 3E8 (3.75 μM), or control IgG (3.75 μM) at 37°C for 20 minutes. The extrinsic coagulation pathway was initiated by adding tissue factor with CaCl₂. Absorbance readings were recorded every 5 seconds at 350 nm, and PT was determined. (C) 3E8 normalized Aβ42-induced intrinsic coagulation in human plasma. Citrated human plasma was incubated with buffer, 3E8 (0.025 μM, 0.075 μM, 0.25 μM), or control IgG (0.25 μM) at 37°C for 20 minutes. Aβ42 (4 μM) with CaCl₂ was added to induce coagulation. 3E8 did not significantly affect Aβ42-induced coagulation at 0.025 μM, while 3E8 corrected Aβ42-induced coagulation at 0.075 μM and 0.25 μM. However, there was no significant difference between 0.075 μM and 0.25 μM 3E8 antibodies. Control IgG did not affect Aβ42-induced coagulation. n = 6. Data are denoted as mean ± SEM. **P ≤ .01, ***P ≤ .001. P > .05 was not significant (n.s.).