N-Acetylmuramyi-L-alanyl-D-isoglutamine (muramyl dipeptide, MDP) 1 was shown (1) to be the minimal and essential s t ructure requi red for adjuvant activity o f bacterial cell wall peptidoglycans. Fur ther , MDP has been found to possess various biological activities, o ther than adjuvant activity, that are exer ted by bacterial cell wall peptidoglycans. Since MDP is such a potent immunomodula ...