The effect of replacement of L-alanine residue by glycine, L-serine or D-alanine in an N-acetylmuramyl-L-alanyl-D-isoglutamine on immunoadjuvancies of molecules.

Substitution of the L-alanine residue by L-serine and glycine in an N-acetylmuramyl-L-alanyl-D-isoglutamine, the minimum structural unit essential to the immunoadjuvancies characteristic of bacterial cell wall peptidoglycans, was shown to bring about significant increase and some decrease, respectively, in the adjuvant abilities of molecules to induce delayed-type hypersensitivity and to stimulate serum antibody levels to ovalbumin when administered to guinea pigs as a water-in-mineral oil emulsion. N-Acetylmuramyl-D-alanyl-D-isoglutamine, on the other hand, was found to be adjuvant-inactive.