Von Willebrand disease "stimulating factor" in porcine plasma

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Abstract
Twenty-five infusions of normal pig plasma, serum, or their Sephadex G-200 and DEAE-cellulose chromatographic fractions were made in 2 pigs with a bleeding diathesis indistinguishable from von Willebrand''s disease and characterized by increases in factor VIII activity significantly above than actually infused. When plasma was fractionated, fraction I from Sephadex G-200 columns contained fibrinogen, factor VIII, and factor VIII stimulating factor. When serum was fractionated, the stimulating factor was in this zone, but fibrinogen and demonstrable factor VIII were lacking. The molecular weight of the stimulating factor may exceed 200,000. When plasma was fractionated, the last protein fraction eluted from the DEAE-cellulose columns contained factor VIII and the stimulating factor. When serum was fractionated, only the stimulating factor was found in this zone. Both factors were clearly separated from fibrinogen, which emerged in the first protein zone. Since the stimulating factor was eluted from DEAE-cellulose at high ionic strength (concentrated in the last major elution peak), the molecule seems to be highly charged at pH 7.4.