Abstract
The effects of in vivo administration of prostaglandin E2 (PGE2) on several hematologic parameters were investigated in intact mice under both steady-state conditions and in mice hematopoietically rebounding following a sublethal injection of cyclophosphamide. Intravenous injection of native PGE2, or 16,16 dimethyl-PGE2, an enzymatically stable analog of PGE2, resulted in the significant suppression of nucleated bone marrow and splenic cellularity, total resident nucleated peritoneal cells, and the absolute number of detectable granulocyte- macrophage progenitor cells (CFU-GM) per femur or spleen when administered for 3 or 7 consecutive days. The in vivo effects of 16,16 dimethyl-PGE2 were more pronounced on the cyclophosphamide-treated mice. Dose titration analysis of the effects of 16,16 dimethyl-PGE2 revealed significant suppression of hematologic parameters over a concentration range of 10 micrograms-10(-5) micrograms/mouse/day (10(- 5) M-10(-11) M). The reduction in total nucleated marrow, splenic, and peritoneal cellularity observed following PGE2 administration resulted from a selective effect on nonspecific esterase-positive cells. In situ morphological analysis of the progeny of CFU-GM proliferating in cultures established from mice treated with PGE2 in vivo indicated that the reduction in absolute CFU-GM observed resulted from a preferential effect on those colony-forming cells restricted to monocyte-macrophage differentiation. Prostaglandin F2 alpha was without stimulatory or inhibitory effects in vivo on the hematopoietic parameters investigated.
