Terminal transferase in normal and leukemic cells

Publisher Summary This chapter presents some of the biological investigations that discuss the position of terminal deoxynucleotidyltransferase (TdT) in the normal hematopoietic system and the use of TdT determination in leukemia research. It covers the methodology used in TdT research and the use of TdT determinations in clinical diagnosis. The basic biological findings provide some deeper understanding of the participation of TdT + cells in the malignant process. It is of considerable utility to use TdT as a marker for differential diagnosis of acute leukemias, but whether the presence of expanded populations of this kind contributes to the disease process, or will provide leverage for therapy, remains to be determined. The fact that cells may express antigens in an aberrant manner is of descriptive interest, but whether aberration has deleterious effects on the cells still is not known. Resolution of these questions should lead deeper into the mechanisms of differentiation in cellular and humoral immunity. Currently, TdT is the only protein that leads to this junction. Tracing this system through its evolutionary origins might lead to the true roots of the immune systems of the higher vertebrates.