1. From the Departments of Plasma Proteins (M.G.R., E.S., K.A.G., J.A.v.M., J.V.) and Experimental Immunohematology (J.P.t.K., P.L.H.), Sanquin Research at CLB, Amsterdam, the Netherlands; and the Department of Vascular Medicine (J.A.v.M.), Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands.