Enrichment of cell populations containing terminal deoxynucleotidyl transferase activity by free flow electrophoresis

Terminal deoxynucleotidyl transferase (TdT) is an enzyme that has been utilized as a biochemical marker for following certain leukemia patients during treatment and remission. The potential usefulness of this enzyme in predicting the onset of relapse before any morphological indications has been demonstrated in chronic myelogenous leukemia patients in blast phase of the disease. In order to be able to detect low levels of TdT activity, especially during remission phase, we have used the technique of free flow electrophoresis to enrich cell populations containing TdT. With this technique we have achieved up to 20-fold enrichment of TdT-positive cell populations from normal human bone marrow, cells from patients with acute lymphoblastic leukemia and chronic myelogenous leukemia in blast phase of the disease. TdT positive cells were not detected in patients with acute myelogenous leukemia and B cell lines. This technique should prove to be useful in early detection of relapse in patients in remission and for enrichment of cell populations containing other biochemical markers.