Evaluation of an endotoxin-specific limulus amebocyte lysate assay using leukocyte-rich plasma for the diagnosis of gram-negative bacterial infection.

We focused our attention on the endotoxin present within and on the surface of white blood cells and attempted to establish a new sample preparation method for endotoxin assays in leukocyte-rich plasma (LRP), taking advantage of the erythrocyte-aggregating property of hydroxyethyl starch. We used an endotoxin-specific turbidimetric kinetic assay, which is the conventional method used to assay endotoxin levels in platelet-rich plasma (PRP). Then, we comparatively assessed the assay results obtained with the endotoxin assay using PRP and LRP. It was found that the sensitivity of endotoxin assay in LRP was 88.5 %, which was superior to 73.1 % of the sensitivity in PRP in the diagnosis of infections caused by gram-negative bacteria. These results suggest that our newly developed LRP endotoxin assay may contribute to an improvement in the rate of sepsis diagnosis.