Acute leukaemia types

Marker patterns in typical acute myeloid leukaemia
CD45 expression in AML
CD45 expression in AML is "weak" i.e. significantly less intense than normal T cells, B cells or monocytes. The typically low side scatter of most blast cells means that myeloid blast cells tend to form a relatively uniform population that is clearly separated from that of lymphocytes on CD45/SSc plots. However, there is some variability releted to indididual subtypes - in AML see particularly our sections on APL and monocytic AML.
Markers of pimitive cell type expected in AML
These markers are generally regarded as indicating less differentiated cells, so may be expressed by any acute leukaemia type. When strongly expressed they have some value in indicating T or B lineage.
Marker	Expectation	Comment
CD34		Frequently expressed, most often in less differentiated forms of AML. Expression often less intense than in lymphoid leukaemias
TDT		Expressed particularly in less differentiated forms of AML. Often on a sub-population of cells; expression usually less intense than in lymphoid leukaemias
CD7		Similar to TdT, CD7 expression is recognised on a proportion of AML, usually those with less differentiated phenotype. Most consistently expressed in T-ALL.
Markers with strong lineage specificity in AML
While not expressed by all cases, when detected by flow cytomwtry MPO can be considered to be lineage-defining marker in AML (or establishing myeloid lineage in MPAL).
Marker	Expectation	Comment
MPO		A strong lineage marker for AML when detected by flow cytometry (though potentially less so by immunocytochemistry)