Evidence for distinct lymphocytic and monocytic populations in a patient with terminal transferase--positive acute leukemia.

Two distinct cell populations with lymphoblastic and monocytic characteristics were separated and characterized by multiple cell markers in a patient with terminal transferase-positive acute acute leukemia. The clinical course and sequential cell marker studies were consistent with the interpretation of a defect at the level of a common stem cell giving rise to a terminal transferase--positive lymphoblastic cell population at diagnosis and, following initial therapy, a terminal transferase--negative monocytic population.