Abstract
We developed a simple new endotoxin-specific assay method that uses Limulus amebocyte lysate (LAL) containing a sufficient amount of a water-soluble (1→3)-β-D-glucan derivative as a blocker of the (1→3)-β-D-glucan-mediated coagulation pathway. The addition of 0.1mg/ml or more of carboxymethylated (1→3)-β-D-glucan completely blocked the activation of LAL by (1→3)-β-D-glucan itself. The assay of endotoxin was unaffected by the presence of 1mg/ml carboxymethylated (1→3)-β-D-glucan. Spiked endotoxin was recovered well from β-glucans by the turbidimetric kinetic method with LAL containing 1mg/ml of carboxymethylated (1→3)-β-D-glucan. Besides, this new LAL formulation was applied for an endotoxin-specific assay by the conventional gel-clot method or the chromogenic method. Gram-negative bacteria were specifically detected by the turbidimetric kinetic method with the LAL formulation. This LAL formulation may be used for an endotoxin-specific assay not only in pharmacology but also in clinical microbiology.
