Terminal deoxynucleotidyl transferase (TdT) and membrane receptors in human leukemia and lymphoma -- first experience with lyophilized cells.

Surface marker analyses and TdT assays were performed on cells from 31 patients. A variety of diagnoses were made and categorized as follows: acute leukemia (group I), non-Hodgkin lymphoma (group II) and diverse diagnoses (group III). Levels of TdT in the range from 0 to 7.9 U/mg lyophilized blasts from the peripheral blood were found in AL. This corresponds to 0-95 U/10(8) cells. Preparations of mononuclear cells from the peripheral blood of healthy donors showed TdT values up to 0.88 U/mg or 10.6 U/10(8) cells. High TdT activity was observed in a patient with AML, type M1 according to the FAB classification. In a patient with ALL (L1) cytostatic treatment effected the clearance of TdT activity from the peripheral blood cells and at the same time induced a significant increase of E rosette forming cells. Combined studies of the TdT activity and cell surface markers may enable us to define remissions and relapses of AL more precisely than it is possible by conventional cytological methods. Within the group II two patients with moderate TdT activities of 1.2 and 1.28 U/mg, respectively, were observed whose cells were of prolymphocytic or unclassifiable appearance, respectively. The TdT assay may be helpful to identify such cells of unknown origin and in addition may provide the means of discrimination between such cases and ALL patients who mostly show high TdT activities. Another result of our studies was the finding of moderate TdT activity of 1.2 U/mg with cells from the pleural effusion of a patient with Hodgkin's disease. Cells from malignant effusions from a patient with melanoma and a patient with teratoid carcinoma showed no TdT activity. Cells form the peripheral blood and from the bone marrow of a patient with blast crisis of CML showed TdT activity of 1.52 and 2.72 U/mg, respectively. Two other patients with blast crisis were negative. Not TdT activity was found in leukemic plasma cells. Our results show that lyophilized cells can be used for determinations of TdT activity. This greatly facilitates multi-parameter studies including cytological, cell surface marker and biochemical analyses.