Terminal deoxynucleotidyl transferase

Terminal deoxyribonucleotidyl transferase (TdT) is an enzyme that adds nucleotides to the 3'-terminal end of DNA. The enzyme is essential for the maturation of hematopoietic stem cells into T-lymphocytes or B-lymphocytes.

An available polyclonal antibody against the terminal deoxynucleotidyl transferase labels T and B precursor cells. In addition, TdT is used for diagnosis and classification of lymphoblastic leukemias and lymphomas as well as myeloid leukemias.

Expression of terminal deoxynucleotidyl transferase is not specific for lymphoblastic lymphomas and leukemias, but is also expressed by some small round cell tumors of childhood (including rhabdomyosarcoma and Ewing's sarcoma).

1. Hantschke M et al (2016) Immunohistological techniques. In: L. Cerroni et al. histopathology of the skin. Springer Publishing House Berlin-Heidelberg p. 32.