Endotoxin-induced alterations in canine granulopoiesis: colony-stimulating factor, colony-forming cells in culture, and growth of cells in diffusion chambers.

Salmonella typhosa endotoxin injected into dogs produced elevated plasma CSF levels, transient leukopenia followed by leukocytosis, and stimulation of marrow granulopoiesis and mobilization of granulocyte-macrophage progenitors cells into the the peripheral circulation. The number of marrow CFU-c decreased to 65% of the control number within 6 h, returned to control levels by 24 h, and increased to 370% of the control number by 48h after endotoxin. The granulopoietic response was supported by a concomitant increase in the M:E ratio, an increased fraction of marrow-derived CFU-c susceptible to 3H-TdR suicide, and increased granulo-monocytopoietic activity of marrow- and peripheral blood-derived cells grown in diffusion chamber cultures. These results are consistent with the concept that endotoxin-induced CSF is a physiologic regulator of canine granulopoiesis, and that canine marrow responds to endotoxin with a significant increase in the concentration of marrow-derived granulocytic progenitors and with mobilization of granulocyte-macrophage progenitors into the peripheral circulation.