[Role of terminal deoxyribonucleotidyl transferase in stimulating lymphocyte DNA synthesis as affected by PHA]

3H-thymidine incorporation was measured in DNA of the human lymphocytes from the peripheral blood after its PHA-stimulation in vitro. The increased PHA-stimulation was established after addition to the medium of exogenous terminal deoxynucleotidyl transferase (TDT) for cultures with small level of PHA-stimulation only. TDT without PHA exerted no stimulating action on the culture of lymphocytes.