Functional maturation of membrane potential changes and superoxide-producing capacity during differentiation of human granulocytes

Abstract

The alterations of stimulus-induced membrane potential changes, superoxide (O2-)-producing capacity and phagocytic activity during differentiation of human granulocytes were investigated in the human leukemia cell lines HL-60 and KG-1 differentiating in vitro and in human leukemic granulocytes obtained from chronic myelogenous leukemia patients. HL-60 cells incubated with dimethyl sulfoxide or with retinoic acid showed progressively increasing O2- production as well as membrane potential changes (depolarization) on contact with phorbol myristate acetate or the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine, with a concomitant increase in the proportion of mature cells of the granulocytic type. Phagocytosis of latex particles, yeast, and oil droplets appeared 24 h after incubation with dimethyl sulfoxide and anteceded the increment of O2- production and membrane potential changes, both of which appeared concomitantly 3 d after incubation with dimethyl sulfoxide. Similar findings were observed when immature and mature granulocytes obtained from chronic myelogenous leukemia patients were stimulated by phorbol ester, the chemotactic peptide, or calcium ionophore A23187, and the amount of O2- production was parallel to the magnitude of membrane potential changes. HL-60 and KG-1 cells incubated for 1-6 d with phorbol myristate acetate showed neither O2- production nor membrane potential changes on contact with phorbol ester, chemotactic peptide, or A23187, although such cells resembled macrophages morphologically, and their phagocytic activity was significantly increased. O2- production and membrane potential changes in normal granulocytes induced by phorbol ester, chemotactic peptide and A23187 were inhibited by 2-deoxyglucose. These findings indicate that the O2--producing system and the system provoking membrane potential changes may develop concomitantly as human granulocytes mature and differentiate, and that the development of these systems and of phagocytic activity may be independently regulated.