[ELISA method using microplates developed with commercial antisera for measuring von Willebrand factor antigen]

The commercial availability of free and peroxidase-conjugated anti-FvW IgG fractions makes it possible to use ELISA methods for FvW: Ag determination in the routine blood coagulation laboratory. A highly sensitive microplate ELISA method was developed in our laboratory (capable of detecting 0.02% FvW: Ag), which proved to be reproducible, quick and not expensive. No significant differences were found between the results attained on different days in 4 control samples (variance analysis), variation coefficient about 12% being observed even for samples with only 11% FvW: Ag. The standard and control sample curves were parallel, which discarded a dilution effect in the assay. The correlation with Laurell's method was r = 0.889 (n = 34, p less than 0.001) and with ristocetin cofactor it was r = 0.677 (n = 19, p less than 0.005).