Measurement of different types of endotoxin in murine plasma by pretreatment with alkaline reagent and kinetic chromogenic Limulus test

Using a combined pretreatment methodology employing an alkaline reagent and a kinetic chromogenic Limulus test using Endospecy®, different types of endotoxins in murine plasma were able to be measured quantitatively. The detection of smooth (S)-form Salmonella abortus equi LPS (S-LPS) was approximately twice as sensitive as Helicobacter pylori LPS in aqueous solution. S-LPS added to whole mouse blood was recovered quantitatively from plasma, but the rough (R)-form S. minnesota LPS was not. The rates of clearance of S-LPS from the circulation following intravenous injection were shown to be different among BALB/c, C3H/HeN and B10Sn mice. Infection of mice with Salmonella typhimurium 3 days earlier resulted in accelerated clearance of subsequently injected LPS from the circulation. Significantly higher amounts of free non-microbe-associated LPS were detected in the blood of mice 1 h after infection with Escherichia coli O111:B4 followed by immediate treatment with ceftazidime, in comparison with non-antibiotic-treated but infected mice.