SELP and Glanzmann thrombasthenia: To examine the interactions of autologous leukocytes with activated platelets at arterial flow conditions, we perfused blood from control subjects and 3 unrelated patients with Glanzmann thrombasthenia (lacking platelet integrin αIIbβ3) at a wall shear rate of 1000 s−1 over a collagen surface, using a previously described microfluidics setup.31 Representative bright-field and fluorescence microscopic images after 4 minutes of flow with control blood showed the presence of large thrombi, with aggregated platelets showing high fibrinogen binding and CD62P expression (Figure 1A and 1B).