Effect of Corynebacterium parvum stimulation on granulopoiesis

Abstract

The intravenous administration of killed Corynebacterium parvum (C. parvum) into C57Bl mice lead to a significant granulocytopenia within 7–15 min after the injection, which was followed by a striking granulocytosis at 2 hr. A second granulocytopenic phase appeared at 12 hr, while normal blood neutrophil counts were observed at 24 hr. The bone marrow granulocyte reserves (MGR) decreased dramatically within 2 hr. A significant decline in the number of band cells and metamyelocytes was noted at 12–72 hr and of myelocytes (MC) at 24 hr. The number of promyelocytes (PMC) and myeloblasts (Bl) presented a significant rise at 24–72 hr after the injection of C. parvum. The labelling indexes were found to be increased at 12–24 hr in both MC and Bl-PMC compartments. The number of granulocyte-macrophage progenitor cells (GM-CFC) increased significantly at 24–28 hr. The proportion of DNA-synthesizing GM-CFC was also found to be elevated 12–24 hr after the injection of the bacterium. The sequence of events which were observed in these experiments indicates that the effect of C. parvum on granulopoiesis starts with a rapid release of MGR into the bloodstream and is followed by an acceleration of proliferation concerning simultaneously both differentiated and committed stem cell compartments of granulocytic series.