Immunomodulation of macrophages by muramyl peptides: recent findings concerning somnogenic activity of muramyl peptides and monokine.

Abstract Synthetic N-acetylmuramyl-L-alanyl-D-isoglutamine, also called MDP for muramyl dipeptide, is a copy of a fragment of bacterial peptidoglycan. MDP and several of its derivatives have marked immunological and pharmacological activities. Besides being adjuvants and capable of producing hyperthermia, they can also induce an increase of slow-wave sleep (SWS). It became apparent in the course of the investigations that in many cases the effects produced by MDP could be mediated by the macrophages. Therefore, after briefly reviewing their influence as macrophage activators, we will focus on certain newer findings such as the somnogenic activity of MDP and of monokine.