Test Details: CD13 is a myeloid antigen, also called as aminopeptidase N (APN). It helps to differentiate acute myelogenous leukaemia / AML in Down's syndrome patients (usually CD13+, CD11b+) from transient myeloproliferative disorder (usually CD13-, CD11b). It also helps to differentiate AML M0 (CD13+) from ALL. Thus CD13 is used as bio marker of myeloid lineage in flow cytometry tests for diagnostic purposes.