Gelation of the amoebocyte lysate of Tachypleus tridentatus by cell wall digest of several gram-positive bacteria and synthetic peptidoglycan subunits of natural and unnatural configurations.

Water-soluble adjuvant-active fractions prepared by digestion of the cell walls from several gram-positive bacteria with an endo-N-acetylmuramidase (Mutanolysin) were shown to gelate the amoebocyte lysate of Tachypleus tridentatus, the Japanese horseshoe crab. This finding was further extended by examination of the clotting activities on the amoebocyte lysate of a synthetic N-acetylmuramyl-L-alanyl-D-isoglutamine and related compounds, either adjuvant-active or -inactive, demonstrating that there are in general close correlations between the abilities to initiate lysate gelation, immunoadjuvancies and pyrogenicities, although there are some exceptions.