Quantitative Limulus lysate assay for endotoxin activity: aggregation of radioiodinated coagulogen monomers.

This communication describes a modification of the Limulus lysate assay which allows precise quantitation of picograms of bacterial lipopolysaccharide activity. The method measures the incorporation of 125I-labeled coagulogen monomers into the lysate clot as a function of lipopolysaccharide concentration. The method is more precise and requires less lysate than the previously described quantitative assays for endotoxin activity.