Study of immunomodulatory properties of N-acetylmuramyl-L-alanyl-D-isoglutamine and N-acetylglucosaminyl-(beta 1----4)-N-acetylmuramyl-L-alanyl-D-isoglutamine.

: The immunomodulatory activities of two synthetic muramylpeptides (MP), a muramyl dipeptide and a glucosaminyl-muramyl dipeptide, have been compared and have been found to exhibit many common features in their effects. In addition, the differential effects of low and high concentrations of MP on the primary humoral immune response in vitro were examined in detail. At high concentrations MP augmented the frequency of induced T-suppressor cells, while at low concentrations the primary immune response was stimulated by enhancement of the antigen-presenting function of accessory cells and by increasing the frequency of induced T-helper cells.