Fig. 6.
Expression of PF4 on the platelet surface after activation.
Citrated PRP either was not activated or it was activated with heparin and HIT IgG, collagen and heparin together, collagen alone, or heparin alone. Activation was arrested after ETP was added and the plasma was chilled on ice. Plasma was removed by centrifugation (for use in the step described in Figure 5). Surface expression of PF4 was determined by the binding of sheep anti-PF4 125I-IgG (dark bars). Open bars represent the nonspecific binding of nonimmune sheep IgG. Graph illustrates the percentage anti-PF4 125I-IgG bound to platelets as a proportion of the total radioactivity added and shows the mean of 2 experiments.
