Platelets from a patient with Glanzmann thrombasthenia do not aggregate with T6 or Thr, do not demonstrate a DW in response to Thr + RGDW, and do not interact with soluble fibrin when activated with T6 or mAb PT25-2. Fibrinogen (50 µg/mL) was added to washed platelets (2 × 10⁸/mL) from a healthy donor (Control) or a patient with Glanzmann thrombasthenia (GT), and then the platelets were treated with the following: (A) T6 (25 μM), Thr (0.2 U/mL), T6 (25 μM) + RGDW (150 μM), or Thr (0.2 U/mL) + RGDW (150 μM). (B) Soluble fibrin (100 μg/mL) was added to washed control or patient platelets and then the platelets were either untreated or treated with 25 μM T6. (C) Washed control or patient platelets (2 × 10⁸/mL) were treated with 15 μg/mL PT25-2 for 20 minutes at room temperature, and then soluble fibrin (100 μg/mL) was added and the change in light transmission was monitored. (D) SEM of samples from a healthy donor and the GT patient 2 minutes after the onset of the DW in the healthy donor.