Managanese stimulates the oxidative brust of differentiated HL-60 cells

Abstract

Incubation with manganese results in a twofold increase in the oxidative burst of differentiated HL-60 cells. This stimulation was characterized by examining the dose response, length of incubation time, and specifity of manganese. Managese only stimulated the burst in cells induced to differentiated with retinoic acid and not in undifferentiated HL-60 cells. Incubation with manganese did not result in a greater number of differentiated cells. The maximum stimulation occurred at 0.2 μmol/L manganese. Stimulation of the oxidative burst required 96 h of incubation with manganese, since cells incubated with the same levels of manganese for the last 24 h of culture did not result in any stimulation. Magnesium, present in the incubation medium at physiological serum levels (820 μmol/L) also stimulated the oxidative burst, whereas iron (0.3 μmol/L), zinc (18 μmol/L), and copper (12 μmol/L) had no effect. To determine whether manganese and magnesium stimulated the burst differently, the initial rates of superoxide anion production was determined. The initial rate of the reaction proceeded rapidly in cells incubated with managnese, whereas there appeared to be a lag before magnesiumtreated cells produced superoxide anion. Thus, manganese seems to stimulate the oxidative burst differently than magnesium.