Expression of vWf by CD34-immunoadsorption column purified marrow cells. Bone marrow cells adhering to the CD34-immunoadsorption column and control microvascular endothelial cells were stained for CD34, HLA-DR, and vWf and analyzed by flow cytometry, as described in the Materials and Methods. (A) Microvascular endothelial cells stained with either vWf antibody plus FITC-conjugated secondary antibody or with the FITC-conjugated secondary antibody; (B) bone marrow cells stained with the FITC-conjugated secondary antibody; (C) bone marrow cells stained with vWf antibody plus FITC-conjugated secondary antibody.