Novel fluoride-stimulated dichlorofluorescin dye oxidation pathway in human leukemia cell lines

NaF stimulation produces a strong dichlorofluorescin (DCFH) dye oxidation signal in HL-60 and PLB-985 human myeloid leukemia cells. This response is comparable in differentiated and undifferentiated cells and occurs in undifferentiated cells when only small amounts of extracellular superoxide or hydrogen peroxide are generated. A comparable response was also observed in human TK-6 B-lymphoblastoid cells. NaF-stimulated DCFH oxidation appears to occur via a pathway that is distinct from respiratory burst oxidant-mediated DCFH oxidation. This alternative pathway may play a role in the normal physiology of myeloid and lymphoid cells, and may represent a confounding variable when DCFH is used to quantify the respiratory burst activity of human phagocytic cells.