Very low concentration of lipopolysaccharide can induce the production of various cytokines and chemokines in human primary monocytes

Objective Lipopolysaccharide (LPS), a component of gram-negative bacteria, is a potent innate immune stimulus. The interaction of LPS with innate immune cells induces the production of proinflammatory cytokines and chemokines, thereby leading to the control of infection. In the present study, we investigated the effect of a wide range of LPS concentrations on the regulation of various proinflammatory cytokines and chemokines in human primary monocytes and T lymphocytes. Results We demonstrated that a very low concentration of LPS could regulate the production of cytokines and chemokines in monocytes but not T lymphocytes. Unexpectedly, very low concentrations of LPS (0.0025 and 0.005 ng/mL) could induce TNF-alpha and IL-6 production, respectively, in monocytes. Our findings provide evidence that in the presence of monocytes, even very low endotoxin contamination could induce cytokine production. We suggest that the recombinant proteins used to investigate immune functions must be thoroughly screened for endotoxins using a highly sensitive method.

Automated summary

This study investigated the regulation of proinflammatory cytokines and chemokines in human primary monocytes and T lymphocytes by various concentrations of Lipopolysaccharide (LPS). The results showed that even very low concentrations of LPS could modulate cytokine production in monocytes but not in T lymphocytes. The study highlights the importance of thorough screening for endotoxins in recombinant proteins used for immune function research.