Analysis of platelet von Willebrand factor antigen.
Platelet lysates were obtained from suspensions of normal washed platelets by freeze-thawing or Triton X-100 lysis. The resultant platelet lysates contained 0.34 +/- 0.15 U/10(9) platelets (n = 8) of von Willebrand factor antigen (vWf:Ag) as determined by radioelectroimmunoassay using a monospecific antibody to vWf:Ag. The vWf:Ag level was higher in platelet lysates prepared from freshly drawn blood than from outdated platelet packs. Platelet lysates from patients with severe von Willebrand's disease type I (n = 2) did not contain detectable vWf:Ag. When normal platelet lysates were analyzed by radiocrossed immunoelectrophoresis in agarose using a monospecific polyclonal antibody to plasma vWf:Ag, two immunochemically identical precipitin peaks were seen. One of the platelet vWf:Ag peaks corresponded in its electrophoretic mobility to plasma vWf:Ag, while the other peak, i.e. platelet vWf:Ag-peak II, migrated to a more anodal position. The presence of the platelet vWf:Ag-peak II suggests structural differences between plasma and platelet vWf:Ag and illustrates previously unrecognized heterogeneity of platelet vWf:Ag.
D000941:Antigens / Q000032:analysis*; D001345:Autoradiography / Q000379:methods; D001792:Blood Platelets / Q000032:analysis*; D004587:Electrophoresis, Agar Gel; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional / Q000379:methods; D008970:Molecular Weight; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000494:pharmacology; D014841:von Willebrand Factor / Q000276:immunology
D000941:Antigens; C029417:Von Willebrand antigen; D014841:von Willebrand Factor; D011092:Polyethylene Glycols; D017830:Octoxynol