[Methodological and clinical evaluation of a microplate assay of endotoxin in whole blood sample]

We have developed a simple, rapid method for determining endotoxin in whole blood using a microtiter plate. The samples were pretreated with 0.66 mol/l nitric acid containing 0.25% Triton X-100; the supernatants were placed in a microtiter plate well, and incubated with endotoxin-specific chromogenic limulus test reagent (Endospecy; Seikagaku Corporation). The calibration curve was linear from 0 to 50 pg/ml of Escherichia coli 0111: B4 endotoxin with a variation coefficient less than 5%. The recovery of endotoxin added to human and experimental animals was about 100% without being affected by dilution. The normal endotoxin level in human whole blood was less than 10 pg/ml in reference to E. coli 0111: B4 endotoxin. The results in 120 patients with various diseases correlated well with those determined by a conventional method using plasma as a sample (r = 0.877; p less than 0.05). Whole blood sample has advantages over plasma in that it allows all endotoxin in a sample to be determined, requires a smaller amount of sample, and has less risk of contamination.