RESUMO
Several (14) commercially prepared, lyophilized Factor VIII concentrates were assayed for VIIIAHF, VIIIAg, and VIIIVWF. Significant levels of VIIIAg (immunologic) and VIIIVWF (von Willebrand Factor) were present in addition to VIIIAHF (Functional VIII, Antihemophilic Factor, Factor VIII coagulant activity). An average of 0.95 units of VIIIVWF (range 0.47--1.7) were present for every 1.0 unit of VIIIAHF (as stated on the manufacturer's label). We suggest that the various lyophilized preparations of Factor VIII concentrate available could be assayed for VIIIVWF and should be tested therapeutically in patients with von Willebrand disease.
Assuntos
Fatores de Coagulação Sanguínea/análise , Fator VIII/análise , Fator de von Willebrand/análise , LiofilizaçãoRESUMO
The authors have developed an improved assay for von Willebrand factor (VIIIVWF) utilizing 4% dimethylsulfoxide (DMSO) to freeze formalin-fixed washed platelets. A platelet aggregometer is used to conduct the assay. The platelets are thawed and an activity curve is established using normal pooled plasma to support ristocetin-induced agglutination. The VIIIVWF level in unknown plasma can then be measured. The platelet preparation is stable for more than a year. Correlation of VIIIVWF measured by this system and Factor VIII antigen (VIIIAg) measured by electroimmunodiffusion was excellent. This is evidence that these two properties reside on the same molecule. Neither VIIIVWF nor VIIIAg correlates well with Factor VIII antihemophilic factor (VIIIAHF).
