Fig. 3.
Binding of HIT F(ab′)2 to platelets.
Platelet-rich plasma (300 × 106 platelets/mL) was mixed with HIT or normal F(ab′)2 (8 μg/mL) and125I-F(ab′)2 tracer in a platelet aggregometer for 12 minutes before heparin (0.5 U/mL) plus collagen (4 μg/mL) was added to induce aggregation. Platelets were sampled 2 minutes before heparin plus collagen and 5 minutes after heparin plus collagen and were centrifuged through a 17% sucrose cushion to separate platelets from unbound F(ab′)2. Symbols indicate the specific binding of patient 1 (▪) and patient 2 (•) F(ab′)2 and nonspecific binding of Normal F(ab′)2 (▴). The gray trace shows a typical aggregation profile. F(ab′)2 bound is the mean of 2 experiments.
