Heme synthesis in normal and leukemic leukocytes.

Incorporation of glycine-2-14C and A-aminolevulinic acid (ALA)-4-14C into heme was studied in normal and leukemic leukocytes. Activities of ALA synthetase, ALA dehydrase, and heme synthetase in these cells were also measured. ALA synthetase activity and/or incorporation of labeled glycine into heme were demonstrated in leukocytes from patients with acute and chronic myelogenous leukemias. Normal granulocytes, normal lymphocytes, and leukocytes from a patient with chronic lymphocytic leukemia could not utilize glycine for heme synthesis. When normal and leukemic leukocytes were incubated with labeled ALA, incorporation of the ALA into heme was observed in all kinds of leukocytes irrespective of their types and stages of maturation. ALA dehydrase and heme synthetase activities were observed in these cells. It is suggested that the leukocytes would lose enzymes for heme synthesis in the process of cellular differentiation, ALA synthe tase being the first enzyme lost.