The biological activity of new tuftsin derivatives--induction of phagocytosis.

Phagocytosis plays a crucial role in a host defense against invading microorganisms. This process can be induced by many phagocytosis stimulating factors. One of them is an endogenous tetrapeptide - tuftsin that occurs in the blood of mammals including human beings. Tuftsin is capable of potentiating granulocyte and macrophage functions such as: phagocytosis, motility, and chemotaxis as well as bactericidal and tumoricidal activity. The other particle able to induce phagocytosis is muramyl dipeptide (MDP), the smallest synthetic glycopeptide of bacterial origin that possesses an immunogenic activity. MDP is known to affect most functions of macrophages. Phagocytosis stimulating properties of a new group of tuftsin and MDP analogues (one tuftsin analogue and four conjugates of tuftsin/retro tuftsin and muramyl dipeptide or nor-muramyl dipeptide) were tested. The results of the study show that all of the examined conjugates are able to generate oxidative burst. The most promising analogues proved to be kd6 and kd7.