Dextran sulfate restores endotoxin detectability in human serum

Area of Science:

• Biochemistry
• Analytical Chemistry
• Microbiology

Background:

• Accurate endotoxin quantification in human serum is crucial for clinical diagnostics and research.
• Low endotoxin recovery (LER) in Limulus amebocyte lysate (LAL) assays compromises accurate measurements.
• Humanpresumably derived inhibitors (HDIs) in serum interfere with LAL assays.

Purpose of the Study:

• To systematically evaluate natural and synthetic polyanions as additives to neutralize HDIs and restore LAL-detectable endotoxin activity in human serum.
• To identify a robust, chemically defined additive for reliable endotoxin quantification in human serum.

Main Methods:

• Screening of polyanions including dextran sulfate, polyacrylic acid, fondaparinux, enoxaparin, and chondroitin sulfate.
• Utilized complementary bacterial growth assays and kinetic chromogenic LAL measurements.
• Optimized concentration of the most effective additive (DS40) and evaluated its performance against pharmacopeial criteria.

Main Results:

• Dextran sulfate (DS40) demonstrated the highest efficacy in neutralizing serum-derived HDIs.
• Optimized DS40 concentration (0.06 mg/mL) restored endotoxin recovery within pharmacopeial acceptance criteria (50-200%).
• DS40 performance was comparable to unfractionated heparin, without interfering with assay linearity or sensitivity.

Conclusions:

• DS40 is a robust, chemically defined additive for overcoming LER in human serum LAL assays.
• DS40 offers advantages over heparin, including superior consistency, lower cost, improved sustainability, and elimination of animal-derived components.
• DS40 enables reliable endotoxin quantification, enhancing the analytical performance of LAL-based assays.