Colony-stimulating activity induced by synthetic muramyl peptides: variation with chemical structure and association with anti-infectious activity.

The in vivo induction of colony-stimulating activity (CSA) by N-acetylmuramyl-L-alanine-D-isoglutamine has been demonstrated recently. In this study we increased our understanding of this property by testing muramyl peptides of several structures and activities for their capacity to induce CSA in vivo. A comparison of the anti-infectious and adjuvant activities of these molecules revealed no correlation between the capacities of these compounds to be adjuvant active and to induce CSA: all adjuvant-inactive compounds induced CSA, and certain adjuvant-active molecules did not induce CSA. In contrast, all anti-infectious compounds induced CSA, but the reverse was not true; some compounds devoid of anti-infection activity were able to induce CSA only if they were adjuvant active.