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The presence of lipopolysaccharide (LPS) as a contaminant in plasmid DNA prepared from Escherichia coli is well documented, and we have previously demonstrated that LPS internalization during adenovirus-mediated gene transfer can generate a toxicity in some primary cell types. We demonstrate here that in addition to adenoviral systems, several commonly used nonviral methods of gene transfer also activate this cell death response in the presence of LPS. Subcomponents of LPS were analyzed and the toxicity was found to be due to the lipid A component of LPS. The LPS-chelating antibiotic polymyxin B, when present at concentration of 10–30 μg/ml, can block this toxicity. Primary cells exposed to lipopolysaccharide (LPS) during transfection undergo a rapid cell death. We demonstrate here that this toxicity is obtained with several types of transfection systems using either adenovirus, glycerol, or cationic lipid to deliver the DNA. The toxicity was found to be due to the lipid A component of LPS. Exposure to ceramide activated a similar toxic response, suggesting that the intracellular delivery of LPS may activate a cell death program related to the ceramide pathway. The LPS-binding antibiotic polymyxin B, when included during transfection, was found to effectively block the toxic response to LPS.
Cotten et al. (Thu,) studied this question.