Modulation of murine hemopoiesis by repeated injections of a glycoprotein extract from Klebsiella pneumoniae.

RU 41740, an immunomodulating agent extracted from the cell wall of Klebsiella pneumoniae, was tested for its ability to modulate hemopoiesis in mice treated intraperitoneally for ten days. In such conditions, a moderate anemia could be observed, which was rapidly reversible after the end of treatment. This anemia may partly result from a decrease of bone marrow erythroid colony forming units (CFU-E), this being incompletely compensated by the intrasplenic erythropoiesis. Moreover, the amount of granulocytes and their progenitors, i.e. granulocyte/macrophage colony forming cells (GM-CFC), increased both in the bone marrow and spleen. It is proposed that this effect of RU 41740 on granulopoiesis, which could explain the better resistance to infections in treated animals as observed elsewhere, is partly related to an increase of colony stimulating activity (CSA).