摘要：

Gelation of a lysate of amebocytes of Limulus, the horseshoe crab, is a sensitive indicator of the presence of a variety of endotoxins. Amebocyte lysate is stable. The reaction between lysate and endotoxin is reproducible and easy to measure. The rate of the reaction between amebocyte lysate and endotoxin is dependent upon the concentration of endotoxin. The reaction is capable of detecting as little as 0.0005 μg per milliliter of endotoxin in human blood plasma and serum. Addition of endotoxin to normal blood resulted in loss of detectable endotoxin activity when undiluted plasma or serum prepared from such blood samples was compared with saline controls. Coagulation resulted in additional loss of endotoxin activity. Preincubation of endotoxin with blood or a low calcium ion concentration was not necessary for the demonstration of inhibition. The inhibitory effect could be eliminated almost completely by dilution of serum or plasma to 1 to 10 per cent. Extraction of plasma with chloroform for 60 minutes permitted essentially total recovery of endotoxin which had been added to whole blood or plasma. The increase in positive tests, following dilution or chloroform extraction of serum or plasma, suggested that the inhibitory nature of blood is primarily the result of reversible binding between endotoxin and serum protein(s), rather than destruction of endotoxin. This test is the most sensitive in vitro assay for endotoxin which has been reported. The technique should have application both for clinical and experimental studies of endotoxin and endotoxemia.

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