RT Journal Article
SR Electronic
T1 Quantitative Limulus lysate assay for endotoxin and the effect of plasma.
JF Journal of Clinical Pathology
JO J Clin Pathol
FD BMJ Publishing Group Ltd and Association of Clinical Pathologists
SP 849
OP 854
DO 10.1136/jcp.44.10.849
VO 44
IS 10
A1 Hurley, J C
A1 Tosolini, F A
A1 Louis, W J
YR 1991
UL http://jcp.bmj.com/content/44/10/849.abstract
AB The effects of plasma and chromogenic substrate on the kinetics of the endotoxin-activated Limulus amoebocyte lysate (LAL) assay were determined. A linear correlation was observed between the rate of development of turbidity (optical density 405) with the LAL reagent and the concentration of endotoxin over a four log ten-fold range. Like chromogenic substrate, the addition of dilution and heat treated plasma to the reaction resulted in an increase in optical density proportional to the concentration of plasma present. The presence of the treated plasma also resulted in an accelerated increase in optical density with comparable results when testing plasma at different concentrations and, additionally, serum. This accelerated increase in optical density may not be recognised in assays that monitor the progress of the reaction at a single time point and may confound assays of plasma samples that use chromogenic substrate. Plasma obtained from endotoxin sensitive and resistant strains of mice showed similar effects. The use of kinetic methodology means that a quantitative assay for endotoxin in plasma can be achieved, its variability comparable with that seen with semiquantitative serial dilution but with greater economy of the LAL reagent.