Terminal deoxynucleotidyl transferase activity in malignant lymphomas.

To determine the usefulness of terminal deoxynucleotidyl transferase enzyme activity as a biochemical marker in the study of lymphoma, we assayed 50 various malignant lymphomas as well as normal lymphoid tissue for this activity. Neoplastic cells from patients with Hodgkin's disease, Burkitt's tumor, Sézary's syndrome, chronic lymphocytic leukemia, leukemic reticuloendotheliosis and lymphocytic lymphomas (poorly differentiated and intermediate) were all without notable enzyme activity. Large-cell tumors of B-cell type were also negative. One of three large-cell tumors without B-cell or T-cell-surface specificity was positive (1.40 nmol per hour per milligram of DNA). Enzyme activity was consistently present only in lymphoblastic lymphomas (all six cases studied), with a mean activity of 7.80 nmol per hour per milligram of DNA. These six cases had heterogeneous surface immunomarkers. We conclude that terminal deoxynucleotidyl transferase is a biochemical marker that will be useful in the study of lymphoma.