Contaminations of cell cultures show severe problems in the research and production industry. The attention turns here particularly to the prevention of any contamination with bacteria, Mycoplasmas, yeast or fungi. For companies that develop substances for therapeutic applications endotoxins are nowadays a main focus.
Endotoxins (Lipopolysaccharides, LPS) are biologically active, structural components of the outer cell membrane of all Gram-negative bacteria. Contaminations of biological solutions (e.g. plasmid DNA, peptide, rec. proteins, antibody) with LPS lead to artefacts and misinterpretations during high-sensitive stimulation experiments (cell cultures or animal models). Therefore prevention, removal & detection of LPS get more and more important1.
Characteristics of LPS
Endotoxine have a hydrophilic polysaccharide and a lipophilic lipid part. Unlike bacteria LPS are very heat and pH stable. Moreover, the amphipatic LPS molecules tend to form large aggregates (> 106 Dalton) in aqueous solutions. Due to the high hydrophobicity they are also very affine to other hydrophobic substances.
LPS & Immune system
The biological activity of endotoxin is associated with the LPS. Toxicity is associated with the lipid component (Lipid A) and immunogenicity is associated with the polysaccharide components. Therefore LPS mediates a variety of proinflammatory and toxic functions which are responsible for much of the pathology in servere infections like sepsis and septic shock. LPS causes a very strong stimulation of different cells of the immune system, such as monocytes, macrophages, B