Acute sterile inflammation--correlation between cellular changes and extramedullary-produced regulators in vivo

Rats with polyvinylpyrrolidone (PVP)-induced sterile inflammation were used as a model in vivo for investigation of granulopoiesis and extramedullary-produced regulators. The data obtained demonstrated the invasion of massive numbers of granulocytes at the site of inflammation (peritoneal cavity) during the first 24 h of the acute phase of inflammation. To meet the organism's needs for granulocytes the activation of granulopoiesis in bone marrow occurred simultaneously. Accelerated production of granulocytic cells is manifested by involvement of granulocytic proliferative compartment in various stages of differentiation (CFU-GM and morphologically recognizable proliferative granulocytes--PG). Together with cellular changes within the granulocytic cells line, the changes in the content of investigated regulators influencing granulopoiesis were observed. At different time intervals the levels of interleukin-6 (IL-6), colony-stimulating activity (CSA), and granulocytic stimulating activity (GSA) were increased locally at the site of inflammation as well as in serum. The data obtained provide evidence that inducible granulopoiesis during the acute phase of inflammation is under the control of extramedullary-produced regulators, thus confirming their role in the regulation of granulocytic production in vivo.