Clone APN1464 recognizes cell surface CD13 antigen, a 150 kDa membrane glycoprotein. The CD13 antigen is highly expressed mostly on myeloid-derived hematopoietic cells including granulocytes, monocytes, mast cells, and GM-progenitor cells. CD13 abundantly expresses on most of the malignant cells of myeloid origin such as AML, CML and also on smaller subset of cancer cells of lymphoid origin. Normal lymphocytes, platelets and erythrocytes do not express CD13. CD13 plays important role in metabolism of biologically active peptides, in phagocytosis, and in bactericidal/tumoricidal immune process. It also serves as a receptor for human coronaviruses (HCV).