Effect of Cadmium on Macrophage U937 Cell Proliferation and Activation

Abstract

The effect of cadmium concentration on the proliferation and activation of U937 cells was studied. Cadmium at different concentrations was incubated with the cell line U937 in culture. Three days later, it was observed that cadmium inhibited the proliferation of the cells in a concentration-dependent manner which may be attributed to the formation of adducts with some growth factors. Later, U937 cells were also pre-treated with phorbol 12- myristate, 13-acetate to transform the cells from the monocyte-like morphology to the macrophage form. The macrophage U937 cells were then incubated with different concentrations of cadmium and the supernatants of the cell cultures were analyzed for the production of nitric oxide via the Griess reaction. Tumour necrosis factor alpha (TNF-α), and the interleukins 6 and 1 (IL 6 and IL 1) were also analyzed by enzyme linked immunosorbent
assay. The results reveal that cadmium significantly enhanced the macrophages to produce nitric oxide and the cytokines when compared to lipopolysaccharide. This shows that cadmium significantly activated macrophages therefore the heavy metal has the capacity of initiating the inflammatory response. It is thus considered as an immunotoxicant.

Keywords: cadmium, hepatotoxic, nephrotoxic, inflammatory, nitric oxide, lipopolysaccharide.