Contamination is a common problem for many immunological laboratories due to the presence of endotoxin in purchased reagents and the subsequent activation of immunological cells. As a result, many scientists need a reliable method of removing endotoxin from experimental samples. Although endotoxin may be removed by adding polymixin B to block effects, occasionally this may not be suitable to the experimental set-up. Therefore, a system that removes endotoxin from necessary reagents is a useful tool. Profos offers such a system that is ready to use and does not require any additional reagents or equipment.
When I recently experienced endotoxin contamination in a reagent needed for experiments with dendritic cells, I was looking for a reliable, easy-to-use system, without the equipment needed for classical removal methods, like ultrafiltration or ion exchange chromatography. EndoTrap blue met all of my needs and came ready-to-use with pre-packed EndoTrap blue columns, equilibration and regeneration buffer. The only required preparation is the storage buffer, which is done simply by adding sodium azide or ethanol to the supplied regeneration buffer. EndoTrap blue has been developed for the removal of endotoxin from aqueous solutions containing high or low molecular weight substances. The EndoTrap ligand is covalently bound to beaded agarose, ensuring minimal leakage of the ligand. You can perform endotoxin removal at a pH between 4 and 9 and a temperature of 4C, using your own buffer (must have a minimum of 50 uM calcium).
EndoTrap blue can be used in a batch (low endotoxin levels) or column mode (high endotoxin levels) with minimum loss of product. I decided to use the column method, simply because we had a high product quantity. First, we wanted to remove endotoxin from a dextransulfate solution. Endotoxin removal rate was about 90%, with a product recovery of 90%. The loss of 10% of the product is probably due to the nature of dextran sulfate. Next, we wanted to remove endotoxin from an antibody raised in our laboratory. Endotoxin removal rate was slightly above 90%, with virtually no loss of the product. The columns can be re-used at least three times if stored and regenerated properly without loss of endotoxin removing capacity.
EndoTrap blue is an appropriate choice for anybody who needs to remove endotoxin from reagents. It is reliable and the only disadvantage is the high cost for the bigger EndoTrap blue columns, which are needed for cleaning large volumes. The newly enriched product family offers a wide choice of EndoTrap systems with different loading volumes and equilibration buffers. The new EndoTrap Red also offers the possibility of working without calcium in the buffers and in the presence chelators like EDTA. The resin, which is filled in the columns, can also be purchased individually in different sizes.
Carl Gebhardt, MD
University of Leipzig
Leipzig, Germany