Preparation of a heterologous antiserum for the determination of von Willebrand factor in human plasma.

A simple method for the preparation of rabbit antiserum against human von Willebrand factor (vWF) from commercial lyophilized factor VIII concentrate is described. vWF antigen (vWFAg)-like protein was obtained by gel filtration of the concentrate on Sepharose 4B. A combination of measurements of protein content by absorbance at 280 nm, and of vWFAg by electroimmunoassay using a commercial antibody, provided the data needed to select the Sepharose-filtered fractions with the highest concentrations of vWFAg-like protein. The immunization scheme used induced high antibody titers from the 45th to the 126th day after the first immunization. The resulting antiserum showed a performance similar to that of a commercial preparation in terms of vWFAg determination by electroimmunoassay and two-dimensional crossed-immunoelectrophoresis.

Preparation of a heterologus antiserum for the determination of von Willebrand factor in human plasma

A simple method for the preparation of rabbit antiserum against human von Willebrand factor (vWF) from commercial lyophilized factor VIII concentrate is described. vWF antigen (vWFAg)-like protein was obtained by gel filtration of the concentrate on Sepharose 4BTM. A combination of measurements of protein content by absorbance at 280 nm, and of vWFAg by electroimmunoassay using a commercial antibody, provided the data needed to select the Sepharosefiltered fractions with the highest concentrations of vWFAg-like protein. The immunization scheme used induced high antibody titers from the 45th to the 126th day after the first immunization. The resulting antiserum showed a performance similar to that of a commercial preparation in terms of vWFAg determination by electroimmunoassay and two-dimensional crossed-immunoelectrophoresis.

Inheritance and prevalence of von Willebrand's disease severe form in a Brazilian population.

Reviewed data suggest that the prevalence of severe von Willebrand's disease is influenced by ethnic and geographic factors. In the State of Rio Grande do Sul, Brazil, seven genealogies in which 11 individuals had a severe expression of von Willebrand's disease were localized. These affected subjects had similar laboratory results and all of them seemed to have resulted from double genetic defects, but the genealogic examination revealed that four of them probably resulted from combinations of autosomal recessive genes, while in the remaining the presence of dominant genes was likely and the involvement of genes for types I or II of von Willebrand's disease was possible. All of their examined relatives were asymptomatic but some of them presented unusual laboratory results, indicative of heterozygosis. The prevalence of severe cases in the surveyed population was higher than expected even when only the recessive forms were considered. It entered the expected values when it was presumed that these were all the cases currently living in the State. Genetic heterogeneity of the severe form was confirmed and it is suggested that the designations 'severe von Willebrand's disease' and 'type III von Willebrand's disease' should not be used as synonyms.

Hereditary combined deficiency of clotting factors V and VIII with involvement of von Willebrand factor.

A family is described in which two brothers, with a significant haemorrhagic disorder, are affected by combined factor V/VIII deficiency. In one of these patients an abnormal decrease of von Willebrand factor was also observed. Family studies suggest that both of the brothers are homozygous for a recessive gene. Normal laboratory results were found in eight other family members although seven of them had reported a mild bleeding tendency. The results indicate that hereditary combined factor V/VIII deficiency is a heterogeneous disorder and that defects of von Willebrand factor might be involved in the aetiology of the disease in some families.

Inherited factor V deficiency. Study of a Brazilian family.

Isolated Factor V deficiency is a very rare inherited coagulopathy. A genealogy of Brazilian Caucasians, where this disorder occurs, is reported. In this family, which was located because 2 affected individuals having the same surname were found by chance, the genealogical and laboratory data suggest an autosomal recessive pattern of inheritance. Nevertheless, the existence of deceased individuals who were reported as symptomatic seems to imply that some heterozygotes may present occasional bleeding episodes.