Capture of LPS by the Limulus blood clot1.

1LPS from E. coli serotype O113:H10 was added to freshly drawn Limulus hemolymph and the preparation was incubated to allow the blood to clot and the clot to retract. The serum was diluted with pyrogen-free deionized water and assayed for residual LPS using the Pyrotell assay, in which a positive result is shown by coagulation of the LAL test reagent (column 3). The assay was sensitive to 0.1 ng/mL LPS both in water and in Limulus plasma (data not shown). Dilution of the samples elevated the minimum detectible concentration of LPS to the values shown in column 4 of the table. The amount of LPS removed from solution by the clot formed from 1 mL of whole blood is shown in column 5. Selected data points from this individual trial were replicated in 3 additional trials.