[Detection of endotoxin in plasma: specificity and value for development and prognosis of infection]

A number of problems may be involved in the detection of endotoxin in plasma of patients using LAL (Limulus amebocyte lysate). When collecting blood or processing samples, contamination with endotoxin or its adsorption to material must be avoided. In our laboratory a kinetic LAL microtiter assay was developed that takes into account plasma-related interferences with the LAL endotoxin reaction by performing an internal standardization in each sample. Negative results do not absolutely exclude the involvement of endotoxins in the underlying disease. High levels of endotoxins do not necessarily reflect the severeness of the clinical status of the patient. Due to nonendotoxin-specific reactions with some complete lysates, false-positive levels may result, e.g., following immunoglobulin therapy. In spite of these limitations, the LAL test remains a valuable tool in the evaluation of gram-negative infections.