Hide and Seek — How Endotoxins Evade Detection in Drug Formulations

Endotoxins (LPS) are experts at hiding. By altering their supramolecular structures, they can mask their biological activity—escaping detection by assays like LAL, HEK-Blue TLR4/MD2, or MAT.

This masking leads to the well-known challenge of Low Endotoxin Recovery (LER), where LPS is present but remains undetected in drug formulations.

A recent study proposed using an ex vivo whole blood assay to reveal hidden endotoxin activity, offering a model that closely mimics the in vivo immune response.
The question, however, remains whether blood sample pooling, which averages responsiveness and gives more robust, less variable test results, may also underestimate the biological response of individual high-responder phenotypes, as has been suggested for MAT.

At LPS-BioSciences, we believe relying on a single approach to study LPS is never enough. That’s why we propose a complementary strategy:

• Direct quantification by LC-MS², targeting hydroxylated fatty acids released from all supramolecular forms of LPS
• Ex vivo whole blood assays to assess biological activity
• Other methods as needed, depending on formulation or risk profile

This multimodal approach helps reduce the risk of missing hidden LPS activity due to LER—because better detection means safer therapeutics.

🔬Curious about the top reasons to use LC-MS2 for the detection of lipopolysaccharides? Check out this link.

Thanks to the study’s authors:
Andra Schromm, Wilmar Correa, Nicolas Gisch, Frank Steiniger, Walter Richter, Guillermo Martinez-de-Tejada, Klaus Brandenburg, and Friedrich von Wintzingerode.