Studies of cellular proliferation in human leukemia. I. Estimation of growth rates of leukemic and normal hematopoietic cells in two adults with acute leukemia given single injections of tritiated thymidine.

Two adults with rapidly progressive acute myeloblastic and myelomonoblastic leukemia were given single injections of tritiated thymidine, and measurements were made of the growth rates of their leukemic and normal hematopoietic cells by radioautographic methods. Although almost all leukemic blasts in both marrow and blood were metabolically active as shown by their ability to incorporate tritiated uridine and leucine in vitro, only 5.6% and 6.