PECAM-1 interactions negatively regulate thrombus formation on collagen under flow.

Whole human blood was pre-incubated with FcγRIIA-blocking antibody IV.3 Fab (10 μg/mL), followed by recombinant human PECAM-1–immunoglobulin chimera alone (0-100 μg/mL) for 10 minutes, before perfusion through collagen-coated microslides at a wall shear rate of 150 seconds⁻¹. Nonadherent cells were removed by washing with Tyrode buffer, and adherent erythrocytes were lysed with 1% (vol/vol) ammonium oxalate. Adherent platelets were lysed in 1% (vol/vol) Triton X-100 and collected for analysis of platelet lactate dehydrogenase (U/mL). In control studies, up to 100 μg/mL human IgG had no effect on thrombus formation on collagen under flow (data not shown).