Inhibition of von Willebrand factor (vWF) binding to recombinant glycoprotein (GP)Ib by IgG anti-human platelet antigen (HPA)-2b determined by enzyme-linked immunoabsorbent assay.

vWF was allowed to bind to GPIbα-Met-145 immobilized on microtitre plate wells via bovine serum albumin-peptide in the presence of ristocetin (⧫) and IgG anti-HPA-2b (▴). Bound vWF was detected with a polyclonal antibody. IgG obtained from an inert group AB serum was used as a negative control (▪). vWF did not bind in the absence of ristocetin (x).