A-325 The positive interference of lipidemia on Limulus amoebocyte lysate (LAL) testing in the presence of (1,3)-ß-glucan (BDG) in serum could be eliminated by the Dextran-X method

Background Limulus amoebocyte lysate (LAL) is widely used in vitro diagnostic assay that can be used as an adjunct test for the diagnosis of invasive fungal infection. This assay was established using a kinetic photometric method. A key aspect of this (1,3)-ß-glucan (BDG)-activated cascade reaction is its characteristic kinetic optical density profile. Interference, which affects the BDG kinetic profile, makes data analysis and interpretation difficult. This interference is roughly classified as being associated with hemolysis, icterus, lipemia (collectively HIL), or other nonspecific factors. Methods In this study, we heated 5% dextran-supplemented serum (1:1 ratio of the volume of serum to 10% dextran solution with 0.1 M Tris-Cl [pH 8.0]) at 80 C for 3.5 min followed by centrifugation at 15,000 × g for 10 minutes (DEX-X Method) largely eliminated lipidemic-associated interference. Results The treated serum LAL BDG reaction curves are more similar to the ideal BDG kinetic profile. The recovery of the introduced glucan has been shown to be acceptable (80-120%) for lipidemic specimens. Conclusion This simple and rapid procedure shows promise as a preanalytical treatment to reduce serum interference in the LAL ß-glucan test for a substantial fraction of samples that currently produce unreported results.