Granulopoiesis associated with the C3HBA tumor in mice.

Female C3H/HeJ mice were inoculated with syngeneic breast adenocarcinoma cells (C3HBA). A progressive neutrophilia developed as the tumors grew. A linear relationship was demonstrated between the tumor diameter and the extent of the neutrophilia. Local tumor excision caused a rapid fall (3 days) in the neutrophil count. Media conditioned with tumor cells, normal mouse kidney, and bone marrow of normal or tumor-bearing mice were prepared. Tumor cell-conditioned medium was found to have marked stimulating activity for granulocytic colony formation of mouse bone marrow cells. Sera from tumor-bearing mice also had colony-stimulating activity. This finding strongly suggested that the neutrophilia was caused by the release of a neutrophil-stimulating factor from the tumor.