Clone APN/1464 recognizes cell surface CD13 antigen, a 150kDa membrane glycoprotein. The CD13 antigen is highly expressed 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 on a smaller subset of cancer cells of lymphoid origin. Normal lymphocytes, platelets and erythrocytes do not express CD13. CD13 plays and important role in phagocytosis, in the bactericidal/tumoricidal immune process, and in the metabolism of biologically active peptides. It also serves as a receptor for human coronaviruses (HCV).