The Role of Colony Stimulating Activity in Modulating Murine Diffusion Chamber Granulopoiesis

Abstract

Effects of high circulating colony stimulating activity (CSA) levels and irradiation induced marrow hypoplasia were studied in CF1 and C57B1/6J host mice upon granulopoiesis in i.p. diffusion chamber (DC) cultures. Serial endotoxin injections resulted in marked elevation of circulating CSA for the first half of an 8 day culture period, and CSA diffused into the chamber environment; this manipulation alone did not significantly accelerate DC cell growth. Pre-irradiation of the host mice produced no elevation of circulating CSA during the early phase of culture, but resulted in signficant stimulation of DC granulopoiesis. Fluctuations in circulating inhibitors of in vitro granulopoiesis did not correlate well with DC cellularity. Endogenous CSA elevation does not provide an effective stimulus per se for granulocyte-monocyte proliferation within DC culture and cannot be solely responsible for mediating the exuberant DC granulopoietic response seen in the pre-irradiated host.