Acid Phosphatase Isoenzyme Profiles in Acute and Chronic Leukemias

We analyzed the acid phosphatase (AcP) isoenzyme profiles of normal and malignant hematopoietic cells using isoelectric focusing followed by diazo staining. Reproducibly defined bands and band complexes could be identified and were correlated with the cellular material analyzed. Different isoenzyme profiles were indeed associated with the various cell types and cell lineages. Lymphoid cells were characterized by the expression of one or two bands at pH 6.0, thus termed L1 or L2 pattern. Myeloid cells showed different isoenzyme profiles (consisting of 3-11 bands) designated M1 and M2. One particular isoenzyme near the cathodal end of the gel could not be inhibited by tarirate, the so-called tartrate-resistant AcP (TRAP). Expression of the TRAP isoenzyme was found in nearly all cases of hairy cell leukemia, but also in a significant number of other B-cell or monocyte derived malignancies. TRAP appears to be an enzymatic parameter for activated B-cells and monocytes. The monocytic cell lineage was clearly documented by the detection of a unique triplet of strongly stained isoenzymes. The AcP isoenzyme profiles represent biochemical cell markers indicating states of activation and lineage of differentiation.