A modified method for application of indirect immunofluorescent staining for factor VIII/vWF to capillary endothelia

Immunofluorescent staining for factor VIII/von Willebrand factor (VIII/vWF) as applied to capillary endothelia has sources of false negativity and false positivity. False negativity occurs because capillary endothelia are not as rich as endothelia of larger vessels in this factor. To overcome this problem we enriched liver endothelium by preincubation with the factor. The source of false positivity is the presence of Fc receptors on freshly isolated capillary endothelia. These receptors may bind antibody to this factor through the Fc portion of the molecule. To overcome this problem we preincubated the cells with IgG not against VIII/vWF (irrelevant antibody) to cover Fc receptors. The results presented indicate that considerable improvement in the immunofluorescent staining of capillary endothelia can be achieved by application of our method.