Effects of in vivo administration of adamantylamide dipeptide on bone marrow granulocyte-macrophage hemopoietic progenitor cells (GM-CFC) and on ability of serum of the treated mice to stimulate GM-CFC colony formation in vitro: Comparison with muramyl dipeptide and glucan

Adamantylamide dipeptide (AdDP), muramyl dipeptide (MDP), and glucan were s hown to increase significantly the numbers of granulocyte-macrophage hemopo ietic progenitor cells (GM-CFC) in the bone marrow of mice. However, wherea s the sera of mice given MDP or glucan were found to stimulate the growth o f colonies from GM-CFC in vitro, i.e. to produce a colony-stimulating activ ity (CSA), administration of AdDP did not lead to this effect. Nevertheless , when serum of mice given AdDP was added to the cultures concomitantly wit h a suboptimal concentration of mouse interleukin-3 (mIL-3), a broad spectr um hemopoietic stimulator, counts of colonies from GM-CFC were significantl y increased, and accelerated growth of the colonies was found as well. This property of AdDP, i.e. its ability to exhibit co-stimulating activity (CoS A) without being able to exhibit CSA, suggests that AdDP acts in hemopoieti c tissues differently as compared with the two other immunomodulators studi ed. It can be hypothesized that the action of AdDP is more specific when co mpared with its natural related compound, MDP, as well as with glucan. Our findings prove the possibility td stimulate by AdDP the granulopoietic comp artment of hemopoiesis and are in agreement with previous observations conc erning the absence of systemic side effects of AdDP. Both these qualities o f AdDP may be advantageous when pondering over contingent clinical utilizat ion of AdDP as hemopoietic stimulator.