Early detection of the Limulus amebocyte lysate reaction evoked by endotoxins.

The gelation of Limulus amebocyte lysate (LAL) evoked by bacterial endotoxins can be detected earlier than with usual methods by using laser scattering photometry to recognize the formation of small particles of clotted enzyme produced when the reaction mixture is agitated. The appearance of these small particles means that the influence of endotoxins has stimulated activation of the clotting enzyme across the LAL cascade, and the timing of their appearance is related to endotoxin concentration. This new method can be used for quick and sensitive endotoxin assay. The average endotoxin level of healthy volunteers was assayed to be 0.0738 pg/ml [0.0312-0.3445 pg/ml] (n = 11) within 70 min from the start of the assay.