CD31 recognizes a 100kDA glycoprotein in endothelial cells and 130kD in platelets. It reacts weakly with mantle zone B-cells, peripheral T-cells, and neutrophils. CD31 can detect vascular endothelium associated antigen and has been used as a marker for benign and malignant human vascular disorders, myeloid leukemia infiltrates and megakaryocytes in normal bone marrow. When compared to Factor VIII and CD34 antibodies, studies have shown CD31 to be a superior marker for angiogenesis. CD31 has been used to measure angiogenesis, which reportedly predicts tumor recurrence. CD31 used in a panel with CD34 and Factor VIII has also been used to mark Kaposi’s sarcoma and angiosarcomas. Other studies have also indicated that CD31 and CD34 can be used as markers for myeloid progenitor cells that recognize different subsets of myeloid leukemia infiltrates (granular sarcomas).