Hematopoietic effects of continuous intravenous infusion of mice with growth factors produced by the WEHI-3 cell line

A method for continuous intravenous infusion of unanesthetized adult C3H/HeJ or W^x/W^vanemic mice was designed using cage immobilization and a tail vein catheter connected to a model 940 Harvard infusion pump. Infusates included: WEHI-3 cell line dialyzed, 5 times concentrated conditioned medium containing multi-colony-stimulating factor (C-SF) interleukin 3 (IL-3); purified murine IL-3; bacterial endotoxin; serum-free medium, or normal saline. Mice were monitored at days 5-7 after infusion for complete peripheral blood counts and production of granulocytes in vitro by explanted marrow in long-term bone marrow cultures. We observed a stimulatory effect of WEHI-3 conditioned medium infusion that was not attributable to endotoxin and produced significant increases in peripheral blood WBC count and neutrophils, colonyforming units in spleen and numbers of granulocyte/macrophage colony-forming unit culture responsive to both C-SF-1 (L cell C-SF) and multi-C-SF in vitro. This infusion method should prove valuable for test of the in vivo effects of purified growth factors and molecularly cloned hematopoietins.