Factor VIII-R Ag.

Anti-Factor VIII-Related Antigen antibody reacts with endothelial cells and neoplastic blood cells. This antibody has helped to establish the endothelial nature of some lesions of disputed histogenesis, e.g. Kaposi’s sarcoma and cardiac myxoma. Not all endothelial cells synthesize (or store) this molecule; therefore, it should not be surprising that not all tumors of endothelial differentiation (benign or malignant) react with this antigen.