University of Tübingen, Department of Internal Medicine II, Division of Hematology, Immunology, and Oncology, Tübingen, Germany.
The cell surface antigen recognized by monoclonal antibody W7C5 is expressed at low levels on human CD34(+) and CD34(-) bone marrow stem cell populations but at high levels on fetal liver CD34(+) cells. To identify the recognized antigen, we performed partial amino acid sequence and MALDI analysis of purified W7C5 antigens. The analyses revealed that MoAb W7C5 detects CD109, a recently cloned glycophosphatidylinositol-linked glycoprotein. The specificity of MoAb W7C5 was further confirmed by the selective recognition of CHO cells transfected with human CD109 cDNA.