Lipopolysaccharide decreases oxygen consumption by Mono Mac 6 cells; an electron paramagnetic resonance oximetry study.

The rate of oxygen consumption in the human acute monocytic leukemia-derived cell line, Mono Mac 6, in response to lipopolysaccharide (LPS) in vitro was measured by electron paramagnetic resonance spectroscopy using an oxygen-sensitive spin-label, 4-oxo-2,2,6,6-tetramethylpiperidine-d16-1-oxyl (15N-PDT). Lipopolysaccharide impaired oxygen consumption in a dose-dependent manner which was shown to be mediated by mitochondrial dysfunction and could be augmented by pretreatment of the cells with interferon-gamma. Treatment of the cells with anti-CD14 monoclonal antibody failed to inhibit the LPS-induced effects on cellular respiration. These results suggest that LPS can directly reduce normal cellular oxygen consumption possibly via a CD14-independent pathway. This alteration of mitochondrial function by LPS may be responsible for the observed cell damage during sepsis.