Organ transplantation and perfusion studies indicate that the spleen plays an important role in the regulation of plasma levels of factor VIII-von Willebrand's factor (FVIII-vWF). To better understand the mechanisms that regulate the FVIII-vWF increase after infusion of 1-deamino-8-D-arginine vasopressin (DDAVP), we have measured factor VIII coagulant activity (FVIII:C) and antigen (FVIII:CAg) and von Willebrand's factor antigen (vWF:Ag) and ristocetin cofactor (vWF:RCof) in 9 asplenic subjects with normal baseline concentrations, in 7 asplenic subjects with high concentrations, and in 14 normal controls with intact spleen. In 'normal' asplenics, all the FVIII-vWF-related measurements increased significantly over baseline values, indicating that responsiveness to DDAVP is not abolished by splenectomy. The maximal vWF:Ag and vWF:RCof responses were no different from those of normal controls, suggesting that DDAVP releases vWF from storage sites other than the spleen. The FVIII:C response was significantly lower than in normal controls, but FVIII:CAg did not differ, making FVIII:CAg higher han FVIII:CAg in 'normal' asplenics. These findings suggest that the spleen, rather than being a storage site for FVIII, is the organ in which a partially inactive form of FVIII acquires full coagulant activity. In 'high' asplenics, all the FVIII-vWF-related measurements increased less than in 'normal' splenics, indicating that long-term elevations of plasma concentrations of FVIII-vWF are accompanied by decreased release from those storage pool(s) mobilized by DDAVP.
|Number of pages||5|
|Publication status||Published - 1982|
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