PORCINE PLATELET VON-WILLEBRAND ANTIGEN-II (VW AGLL) - INHIBITORY EFFECT ON COLLAGEN-INDUCED AGGREGATION AND COMPARATIVE DISTRIBUTION WITH HUMAN PLATELETS

Von Willebrand factor (vWF) is synthesized by human endothelial cells and megakaryocytes as a large precursor, the pre-provWF, which is fina lly cleaved into the propolypeptide of vWF (pp-vWF) and the mature vWF . We have purified in parallel the pp-vWF and the GP IIb-IIIa from por cine platelets. The N-terminus comparative analysis of porcine pp-vWF with respect to other species revealed more than a 75% and 65% homolog y with the bovine and human pp-vWF, respectively. Purified pp-vWF inhi bited collagen-induced platelet aggregation in porcine platelet rich p lasma (PRP) and specifically binds to collagen. Polyclonal antibody pa bBp19 against the purified protein was prepared and characterized by E LISA, Western-blot and immunocytochemistry. The distribution of pp-vWF in soluble and membrane fractions from pig platelets has been perform ed by immunolabeling detection. pabBp19 did not blot human platelet ly sates but human pp-vWF was detectable using the antibody Frieda 013091 . Cell distribution and quantification studies of human and porcine pl atelet pp-vWF showed that the protein exists in the soluble and membra ne fractions and its pattern is similar in both species.